Millennials were the largest generation group in the United States in 2024, with an estimated population of ***** million. Born between 1981 and 1996, Millennials recently surpassed Baby Boomers as the biggest group, and they will continue to be a major part of the population for many years. The rise of Generation Alpha Generation Alpha is the most recent to have been named, and many group members will not be able to remember a time before smartphones and social media. As of 2024, the oldest Generation Alpha members were still only aging into adolescents. However, the group already makes up around ***** percent of the U.S. population, and they are said to be the most racially and ethnically diverse of all the generation groups. Boomers vs. Millennials The number of Baby Boomers, whose generation was defined by the boom in births following the Second World War, has fallen by around ***** million since 2010. However, they remain the second-largest generation group, and aging Boomers are contributing to steady increases in the median age of the population. Meanwhile, the Millennial generation continues to grow, and one reason for this is the increasing number of young immigrants arriving in the United States.

Between the beginning of January 2020 and June 14, 2023, of the 1,134,641 deaths caused by COVID-19 in the United States, around 307,169 had occurred among those aged 85 years and older. This statistic shows the number of coronavirus disease 2019 (COVID-19) deaths in the U.S. from January 2020 to June 2023, by age.

In the 21st century, homicide has been responsible for roughly 0.6 to 0.8 percent of all deaths in the United States. While this is higher than annual rates observed in the post-WWII era, it is significantly less than the rates seen between the mid-1960s and mid-1990s, where over one percent of all deaths in the U.S. were from homicide in most years. Crime wave of the late 20th century There are a variety of factors attributed to the crime wave of the late 20th century. Demographic factors include the arrival of the baby boomer generation into adolescence, a rise in urbanization, and a growing share of the population living in poverty. A series of economic recessions saw the prosperity of the post-war period come to an end, and many turned to crime in response.

This coincided with a rise in the illegal drug trade and drug consumption, as well as the federal government's response via the so-called "War on Drugs", which changed the dynamics of inter-city crime and law enforcement for decades to come. A rise in incarceration rates has been cited as one of the reasons for the "Great Crime Decline" of the 1990s, although many are skeptical of its long-term effectiveness.

In 1800, the population of the modern-day territory of Iran was approximately 6.3 million. This figure would see modest growth throughout the 19th century, as several wars and a mass famine in 1870-1871 (modern estimates put its death toll at around 1.5 million people) were largely balanced out by a surge in migration to Iran; this migration came as the Russian Empire expanded into the Caucuses, and caused a wave of refugees to flee southwards to avoid forced expulsion and ethnic cleansing in the North Caucasus region, particularly from 1864 onwards. As a result, the population of Iran reached ten million by the turn of the 20th century.

Twentieth century growth Iran’s population would begin to grow rapidly in the 20th century, as the discovery of oil in the country in 1908 led to an economic boom, and the socio-economic reforms implemented under Reza Shah would see a number of medical and healthcare advancements across the country. Although unpopular with religious fundamentalists, Reza Shah's reforms had long-term influence on the demographic development of Iran, even after his abdication in 1941. Following the Second World War, Iran became increasingly westernized and developed relatively strong relations with the U.S.; however, western influence, economic imbalances and the oppression of the Mohammed Reza Shah's regime became the driving forces behind the Iranian Revolution, which was one of the most significant moments in the history of the region.

Growth after the Revolution The 1979 Iranian Revolution saw the removal of the Shah and an end to Iran's so called westernization; the monarchy was replaced by an Islamic, theocratic regime led by the Supreme Leader, Ayatollah Ruhollah Khomeini. During Khomeini's decade in charge he oversaw Iran's transition into an Islamic Republic, which implemented radical political and cultural changes in the country, and this coincided with an increased population growth rate in the 1980s. This growth was promoted by the Iranian government, who encouraged a baby boom during the Iran–Iraq War between 1980 and 1988, as part of an effort to increase future Iranian military manpower. As a result of this strategy, the population of Iran would grow from approximately 38.6 million in 1980 to over 56 million just a decade later. Following the implementation of a UN-brokered ceasefire in 1988, population growth in Iran would slow, as economic sanctions and government implementation of family planning policies would lead to a drop in fertility. Population growth has continued steadily into the 21st century, however, and in 2020, Iran is estimated to have a population of 84 million.