About this dataset

Context

The dataset tabulates the Mcallen population over the last 20 plus years. It lists the population for each year, along with the year on year change in population, as well as the change in percentage terms for each year. The dataset can be utilized to understand the population change of Mcallen across the last two decades. For example, using this dataset, we can identify if the population is declining or increasing. If there is a change, when the population peaked, or if it is still growing and has not reached its peak. We can also compare the trend with the overall trend of United States population over the same period of time.

Key observations

In 2023, the population of Mcallen was 146,593, a 1.39% increase year-by-year from 2022. Previously, in 2022, Mcallen population was 144,582, an increase of 0.58% compared to a population of 143,755 in 2021. Over the last 20 plus years, between 2000 and 2023, population of Mcallen increased by 39,397. In this period, the peak population was 146,593 in the year 2023. The numbers suggest that the population has not reached its peak yet and is showing a trend of further growth. Source: U.S. Census Bureau Population Estimates Program (PEP).

Content

When available, the data consists of estimates from the U.S. Census Bureau Population Estimates Program (PEP).

Data Coverage:

• From 2000 to 2023

Variables / Data Columns

• Year: This column displays the data year (Measured annually and for years 2000 to 2023)
• Population: The population for the specific year for the Mcallen is shown in this column.
• Year on Year Change: This column displays the change in Mcallen population for each year compared to the previous year.
• Change in Percent: This column displays the year on year change as a percentage. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Year. You can refer the same here

Graph and download economic data for Population Estimate, Total, Not Hispanic or Latino, Two or More Races (5-year estimate) in Hidalgo County, TX (B03002009E048215) from 2009 to 2023 about Hidalgo County, TX; Mcallen; TX; non-hispanic; estimate; persons; 5-year; population; and USA.

About this dataset

Context

The dataset tabulates the Mcallen population over the last 20 plus years. It lists the population for each year, along with the year on year change in population, as well as the change in percentage terms for each year. The dataset can be utilized to understand the population change of Mcallen across the last two decades. For example, using this dataset, we can identify if the population is declining or increasing. If there is a change, when the population peaked, or if it is still growing and has not reached its peak. We can also compare the trend with the overall trend of United States population over the same period of time.

Key observations

In 2022, the population of Mcallen was 144,579, a 0.48% increase year-by-year from 2021. Previously, in 2021, Mcallen population was 143,882, an increase of 1.04% compared to a population of 142,395 in 2020. Over the last 20 plus years, between 2000 and 2022, population of Mcallen increased by 37,383. In this period, the peak population was 144,579 in the year 2022. The numbers suggest that the population has not reached its peak yet and is showing a trend of further growth. Source: U.S. Census Bureau Population Estimates Program (PEP).

Content

When available, the data consists of estimates from the U.S. Census Bureau Population Estimates Program (PEP).

Data Coverage:

• From 2000 to 2022

Variables / Data Columns

• Year: This column displays the data year (Measured annually and for years 2000 to 2022)
• Population: The population for the specific year for the Mcallen is shown in this column.
• Year on Year Change: This column displays the change in Mcallen population for each year compared to the previous year.
• Change in Percent: This column displays the year on year change as a percentage. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Year. You can refer the same here

About this dataset

Context

The dataset tabulates the population of Mcallen by gender across 18 age groups. It lists the male and female population in each age group along with the gender ratio for Mcallen. The dataset can be utilized to understand the population distribution of Mcallen by gender and age. For example, using this dataset, we can identify the largest age group for both Men and Women in Mcallen. Additionally, it can be used to see how the gender ratio changes from birth to senior most age group and male to female ratio across each age group for Mcallen.

Key observations

Largest age group (population): Male # 10-14 years (6,561) | Female # 5-9 years (5,443). Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Age groups:

• Under 5 years
• 5 to 9 years
• 10 to 14 years
• 15 to 19 years
• 20 to 24 years
• 25 to 29 years
• 30 to 34 years
• 35 to 39 years
• 40 to 44 years
• 45 to 49 years
• 50 to 54 years
• 55 to 59 years
• 60 to 64 years
• 65 to 69 years
• 70 to 74 years
• 75 to 79 years
• 80 to 84 years
• 85 years and over

Scope of gender :

Please note that American Community Survey asks a question about the respondents current sex, but not about gender, sexual orientation, or sex at birth. The question is intended to capture data for biological sex, not gender. Respondents are supposed to respond with the answer as either of Male or Female. Our research and this dataset mirrors the data reported as Male and Female for gender distribution analysis.

Variables / Data Columns

• Age Group: This column displays the age group for the Mcallen population analysis. Total expected values are 18 and are define above in the age groups section.
• Population (Male): The male population in the Mcallen is shown in the following column.
• Population (Female): The female population in the Mcallen is shown in the following column.
• Gender Ratio: Also known as the sex ratio, this column displays the number of males per 100 females in Mcallen for each age group.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Gender. You can refer the same here

Graph and download economic data for Resident Population in Hidalgo County, TX (TXHIDA5POP) from 1970 to 2024 about Hidalgo County, TX; Mcallen; residents; TX; population; and USA.

Graph and download economic data for Population Estimate, Total, Hispanic or Latino (5-year estimate) in Hidalgo County, TX (B03002012E048215) from 2009 to 2023 about Hidalgo County, TX; Mcallen; latino; hispanic; TX; estimate; persons; 5-year; population; and USA.

About this dataset

Context

The dataset tabulates the Mcallen population distribution across 18 age groups. It lists the population in each age group along with the percentage population relative of the total population for Mcallen. The dataset can be utilized to understand the population distribution of Mcallen by age. For example, using this dataset, we can identify the largest age group in Mcallen.

Key observations

The largest age group in Mcallen, TX was for the group of age 10 to 14 years years with a population of 11,607 (8.07%), according to the ACS 2019-2023 5-Year Estimates. At the same time, the smallest age group in Mcallen, TX was the 85 years and over years with a population of 2,185 (1.52%). Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates

Age groups:

• Under 5 years
• 5 to 9 years
• 10 to 14 years
• 15 to 19 years
• 20 to 24 years
• 25 to 29 years
• 30 to 34 years
• 35 to 39 years
• 40 to 44 years
• 45 to 49 years
• 50 to 54 years
• 55 to 59 years
• 60 to 64 years
• 65 to 69 years
• 70 to 74 years
• 75 to 79 years
• 80 to 84 years
• 85 years and over

Variables / Data Columns

• Age Group: This column displays the age group in consideration
• Population: The population for the specific age group in the Mcallen is shown in this column.
• % of Total Population: This column displays the population of each age group as a proportion of Mcallen total population. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Age. You can refer the same here

Historical dataset of population level and growth rate for the McAllen metro area from 1950 to 2025.

Resident Population in McAllen-Edinburg-Mission, TX (MSA) was 914.82000 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in McAllen-Edinburg-Mission, TX (MSA) reached a record high of 914.82000 in January of 2024 and a record low of 573.39800 in January of 2000. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in McAllen-Edinburg-Mission, TX (MSA) - last updated from the United States Federal Reserve on May of 2025.

U.S. Census Bureau QuickFacts statistics for McAllen city, Texas. QuickFacts data are derived from: Population Estimates, American Community Survey, Census of Population and Housing, Current Population Survey, Small Area Health Insurance Estimates, Small Area Income and Poverty Estimates, State and County Housing Unit Estimates, County Business Patterns, Nonemployer Statistics, Economic Census, Survey of Business Owners, Building Permits.

The Rio Grande Valley (RGV) in South Texas has one of the highest prevalence of obesity and type 2 diabetes (T2D) in the United States (US). We report for the first time the T2D prevalence in persons with HIV (PWH) in the RGV and the interrelationship between T2D, cardiometabolic risk factors, HIV-related indices, and antiretroviral therapies (ART). The PWH in this study received medical care at Valley AIDS Council (VAC) clinic sites located in Harlingen and McAllen, Texas. Henceforth, this cohort will be referred to as Valley AIDS Council Cohort (VACC). Cross-sectional analyses were conducted using retrospective data obtained from 1,827 registries. It included demographic and anthropometric variables, cardiometabolic traits, and HIV-related virological and immunological indices. For descriptive statistics, we used mean values of the quantitative variables from unbalanced visits across 20 months. Robust regression methods were used to determine the associations. For comparisons, we used cardiometabolic trait data obtained from HIV-uninfected San Antonio Mexican American Family Studies (SAMAFS; N = 2,498), and the Mexican American population in the National Health and Nutrition Examination Survey (HHANES; N = 5,989). The prevalence of T2D in VACC was 51% compared to 27% in SAMAFS and 19% in HHANES, respectively. The PWH with T2D in VACC were younger (4.7 years) and had lower BMI (BMI 2.43 units less) when compared to SAMAFS individuals. In contrast, VACC individuals had increased blood pressure and dyslipidemia. The increased T2D prevalence in VACC was independent of BMI. Within the VACC, ART was associated with viral load and CD4+ T cell counts but not with metabolic dysfunction. Notably, we found that individuals with any INSTI combination had higher T2D risk: OR 2.08 (95%CI 1.67, 2.6; p < 0.001). In summary, our results suggest that VACC individuals may develop T2D at younger ages independent of obesity. The high burden of T2D in these individuals necessitates rigorously designed longitudinal studies to draw potential causal inferences and develop better treatment regimens.

About this dataset

Context

The dataset tabulates the data for the Mcallen, TX population pyramid, which represents the Mcallen population distribution across age and gender, using estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates. It lists the male and female population for each age group, along with the total population for those age groups. Higher numbers at the bottom of the table suggest population growth, whereas higher numbers at the top indicate declining birth rates. Furthermore, the dataset can be utilized to understand the youth dependency ratio, old-age dependency ratio, total dependency ratio, and potential support ratio.

Key observations

• Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Mcallen, TX, is 35.7.
• Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Mcallen, TX, is 21.1.
• Total dependency ratio for Mcallen, TX is 56.8.
• Potential support ratio, which is the number of youth (working age population) per elderly, for Mcallen, TX is 4.7.

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Age groups:

• Under 5 years
• 5 to 9 years
• 10 to 14 years
• 15 to 19 years
• 20 to 24 years
• 25 to 29 years
• 30 to 34 years
• 35 to 39 years
• 40 to 44 years
• 45 to 49 years
• 50 to 54 years
• 55 to 59 years
• 60 to 64 years
• 65 to 69 years
• 70 to 74 years
• 75 to 79 years
• 80 to 84 years
• 85 years and over

Variables / Data Columns

• Age Group: This column displays the age group for the Mcallen population analysis. Total expected values are 18 and are define above in the age groups section.
• Population (Male): The male population in the Mcallen for the selected age group is shown in the following column.
• Population (Female): The female population in the Mcallen for the selected age group is shown in the following column.
• Total Population: The total population of the Mcallen for the selected age group is shown in the following column.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Age. You can refer the same here

Graph and download economic data for Unemployment Rate in McAllen-Edinburg-Mission, TX (MSA) (LAUMT483258000000003A) from 1990 to 2024 about Mcallen, household survey, TX, unemployment, rate, and USA.

Graph and download economic data for Percent of Population Below the Poverty Level (5-year estimate) in Hidalgo County, TX (S1701ACS048215) from 2012 to 2023 about Hidalgo County, TX; Mcallen; percent; poverty; TX; 5-year; population; and USA.

About this dataset

Context

The dataset tabulates the Non-Hispanic population of Mcallen by race. It includes the distribution of the Non-Hispanic population of Mcallen across various race categories as identified by the Census Bureau. The dataset can be utilized to understand the Non-Hispanic population distribution of Mcallen across relevant racial categories.

Key observations

Of the Non-Hispanic population in Mcallen, the largest racial group is White alone with a population of 12,431 (64.23% of the total Non-Hispanic population).

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Racial categories include:

• White
• Black or African American
• American Indian and Alaska Native
• Asian
• Native Hawaiian and Other Pacific Islander
• Some other race
• Two or more races (multiracial)

Variables / Data Columns

• Race: This column displays the racial categories (for Non-Hispanic) for the Mcallen
• Population: The population of the racial category (for Non-Hispanic) in the Mcallen is shown in this column.
• % of Total Population: This column displays the percentage distribution of each race as a proportion of Mcallen total Non-Hispanic population. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Race & Ethnicity. You can refer the same here

About this dataset

Context

The dataset tabulates the population of Mcallen by gender, including both male and female populations. This dataset can be utilized to understand the population distribution of Mcallen across both sexes and to determine which sex constitutes the majority.

Key observations

There is a slight majority of female population, with 50.47% of total population being female. Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Scope of gender :

Please note that American Community Survey asks a question about the respondents current sex, but not about gender, sexual orientation, or sex at birth. The question is intended to capture data for biological sex, not gender. Respondents are supposed to respond with the answer as either of Male or Female. Our research and this dataset mirrors the data reported as Male and Female for gender distribution analysis. No further analysis is done on the data reported from the Census Bureau.

Variables / Data Columns

• Gender: This column displays the Gender (Male / Female)
• Population: The population of the gender in the Mcallen is shown in this column.
• % of Total Population: This column displays the percentage distribution of each gender as a proportion of Mcallen total population. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Mcallen Population by Race & Ethnicity. You can refer the same here

Parameter estimates and robust standard errors of most supported model describing diurnal habitat selection by sandhill cranes on their primary wintering area, the Middle Rio Grande Valley of central New Mexico.

Graph and download economic data for Population Estimate, Total, Hispanic or Latino, American Indian and Alaska Native Alone (5-year estimate) in Hidalgo County, TX (B03002015E048215) from 2009 to 2023 about Hidalgo County, TX; Mcallen; AK; American Indian; latino; hispanic; TX; estimate; persons; 5-year; population; and USA.

We captured 235 Gray Hawks (Buteo plagiatus) in the Lower Rio Grande Valley (Hidalgo, Willacy, and Cameron counties) of Texas from 6 February 2003 to 8 April 2023. We identified birds in five molt cycles: 115 birds in their first cycle, 16 in their second cycle, 73 in at least their second cycle, 19 in at least their third cycle, and 12 in at least their fourth cycle. Of these, we documented 15 instances of preformative molt, six instances where birds had an incomplete second prebasic molt, resulting in one to three retained juvenile rump feathers and/or wing coverts, and 18 instances where incomplete prebasic molts resulted in birds with multiple generations of flight feathers. We also present morphometric data from 144 Gray Hawks (nestlings and first-cycle birds captured prior to 1 October excluded). These results from the Lower Rio Grande Valley, on both molting strategies and measurements, differed in some respects from other sources based on the entire Gray Hawk population, most no..., We primarily used bal-chatri traps with 8–10 cm nooses made from 13.6 kg test monofilament fishing line to capture free-flying Gray Hawks (Bub 1991). We also used phai traps, bow net, and mist nets with a mounted Great Horned Owl (Bubo virginianus) lure near nest sites (Bloom et al. 2007). We fit Gray Hawks with individually numbered U.S. Geological Survey (USGS) aluminum bands, and birds banded after November 2019 also received an aluminum color band (Acraft Sign and Nameplate Co. Ltd., Edmonton, Alberta, Canada and Anillas Talismán S. L., Madrid, Spain). We recorded hallux claw length, tail length, mass, wing chord, and exposed culmen length for each bird (Hull and Bloom 2001, Pyle 2008). Measurements were obtained using digital scales and calipers, clear plastic rulers, and metal wing rules with a 90-degree stop following the techniques outlined in Pyle (2008). We did not measure tarsus length because this was too difficult to standardize among multiple banders. Measurements on 196 b..., , # Data from: Photos and banding data from: Molt and body measurements for Gray Hawks in the Lower Rio Grande Valley of Texas

https://doi.org/10.5061/dryad.c59zw3rjn

Description of the data and file structure

From 6 February 2003 to 8 April 2023, we captured 235 Gray Hawks, 201 newly banded birds and 34 recaptures of previously banded birds. We categorized molt and plumage cycles using Humphrey-Parkes-Howell terminology, and age classes according to molt cycle (Howell et al. 2003, Clark and Pyle 2015, Pyle et al. 2021). We separated age classes into local (nestlings, unable to fly), first cycle (between fledging and dropping the first primary during the second prebasic molt, or HY/SY in calendar-based terms), second cycle (between this and dropping the first primary during the third prebasic molt, or SY/TY), minimum second cycle (AHY/ASY), minimum third cycle (ASY/ATY) , and minimum fourth cycle (ATY/A4Y). When examining flight feathers, w...

description: Organochlorine, trace element, and petroleum hydrocarbon contaminants were examined in sediment and biota from the Lower Rio Grande Valley, Texas. The study was designed to monitor organochlorine contaminants and provide baseline information on trace elements and petroleum hydrocarbons. The detection of 15 different organochlorine insecticides in a variety of environmental compartments is indicative of the widespread agricultural development in the valley and of the persistence of the pesticides. DDE and toxaphene residues, in particular, were elevated compared to national baseline data. This continues a trend which has been documented in previous studies. The maximum levels of DDE and toxaphene in fish are much lower than the levels found by White et al. (1983) in a study conducted 8 to 10 years prior to this study. The data indicates that DDE levels are gradually declining. The geometric mean in fish was below the 1.0 ppm level recommended for the protection of aquatic life. Several fish samples still exceeded this level, though. The levels of DDE in spiny softshell turtles, which are highly piscivorous, exceeded the 1.0 ppm levels. The biological significance of these residues in turtles is unknown. The DDE levels in fish are sufficient to cause some degree of eggshell thinning in fish-eating birds, but are not expected to cause bird population declines. Toxaphene was detected in fish at levels that have been associated with reduced growth, reduced fecundity and abnormal bone growth. Examining several years of data from station 16 of the National Contaminants Biomonitoring Program indicated that toxaphene residues have not declined like those of DDE. This may be due to the cancellation of toxaphene by EPA which allowed for the use of existing stocks through 1986. Four locations had some of the highest DDE and toxaphene residues in turtles and fish: 1) Llano Grande on the Arroyo Colorado, 2) Laguna Atascosa and Cayo Atascosa before it flows into Laguna Atascosa, 3) the Rio Grande above Anzalduas Dam, and 4) the Resaca de los Cuates. Three of these four locations are bodies of water that have been impounded. Trace elements were generally low in biota, but some fish samples had elevated chromium and copper levels. Three fish samples exceeded the tissue level of 4.0 ppm dry weight which is considered to be an indication of chromium contamination, and six fish samples exceeded the national baseline 85th percentile for copper. Aliphatic hydrocarbons (alkanes) were found above detection most frequently in spiny softshell turtles, fish, blue crabs, and cotton rats. The highest alkane residues were detected in fish. Both petroleum hydrocarbon and biogenic sources contributed to the concentrations found in this study. The data indicates that biogenic sources were the major contributors of aliphatic hydrocarbons. PAHs were found in five sediment samples. Two samples containing several PAHs. The sample with the highest levels was from the Turning Basin of the Brownsville Ship Channel. The second highest level sample was from an oxbow within the city limits of Brownsville. The levels of PAHs in sediment are comparable to areas that are considered slightly to moderately contaminated.; abstract: Organochlorine, trace element, and petroleum hydrocarbon contaminants were examined in sediment and biota from the Lower Rio Grande Valley, Texas. The study was designed to monitor organochlorine contaminants and provide baseline information on trace elements and petroleum hydrocarbons. The detection of 15 different organochlorine insecticides in a variety of environmental compartments is indicative of the widespread agricultural development in the valley and of the persistence of the pesticides. DDE and toxaphene residues, in particular, were elevated compared to national baseline data. This continues a trend which has been documented in previous studies. The maximum levels of DDE and toxaphene in fish are much lower than the levels found by White et al. (1983) in a study conducted 8 to 10 years prior to this study. The data indicates that DDE levels are gradually declining. The geometric mean in fish was below the 1.0 ppm level recommended for the protection of aquatic life. Several fish samples still exceeded this level, though. The levels of DDE in spiny softshell turtles, which are highly piscivorous, exceeded the 1.0 ppm levels. The biological significance of these residues in turtles is unknown. The DDE levels in fish are sufficient to cause some degree of eggshell thinning in fish-eating birds, but are not expected to cause bird population declines. Toxaphene was detected in fish at levels that have been associated with reduced growth, reduced fecundity and abnormal bone growth. Examining several years of data from station 16 of the National Contaminants Biomonitoring Program indicated that toxaphene residues have not declined like those of DDE. This may be due to the cancellation of toxaphene by EPA which allowed for the use of existing stocks through 1986. Four locations had some of the highest DDE and toxaphene residues in turtles and fish: 1) Llano Grande on the Arroyo Colorado, 2) Laguna Atascosa and Cayo Atascosa before it flows into Laguna Atascosa, 3) the Rio Grande above Anzalduas Dam, and 4) the Resaca de los Cuates. Three of these four locations are bodies of water that have been impounded. Trace elements were generally low in biota, but some fish samples had elevated chromium and copper levels. Three fish samples exceeded the tissue level of 4.0 ppm dry weight which is considered to be an indication of chromium contamination, and six fish samples exceeded the national baseline 85th percentile for copper. Aliphatic hydrocarbons (alkanes) were found above detection most frequently in spiny softshell turtles, fish, blue crabs, and cotton rats. The highest alkane residues were detected in fish. Both petroleum hydrocarbon and biogenic sources contributed to the concentrations found in this study. The data indicates that biogenic sources were the major contributors of aliphatic hydrocarbons. PAHs were found in five sediment samples. Two samples containing several PAHs. The sample with the highest levels was from the Turning Basin of the Brownsville Ship Channel. The second highest level sample was from an oxbow within the city limits of Brownsville. The levels of PAHs in sediment are comparable to areas that are considered slightly to moderately contaminated.