During the mid-1800s, the American population followed the country’s Manifest Destiny; as land was acquired, westward migration toward the Pacific occurred. The activity uses a web-based map and is tied to the C3 Framework.

Learning outcomes:

· Students will be able to explain the reasons for the westward emigration of the American population during the 1800s.· Students will be able to compare the major trails.

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This activity will no longer be maintained after June 16, 2025. Current lessons are available in the K-12 Classroom Activities Gallery.

This activity uses Map Viewer.ResourcesMapTeacher guide Student worksheetGet startedOpen the map.Use the teacher guide to explore the map with your class or have students work through it on their own with the worksheet.New to GeoInquiriesTM? See Getting to Know GeoInquiries.Social Studies standardsC3: D2.His.14.9-12 – Analyze multiple and complex causes and effects of events in the past.C3: D2.His.4.9-12 – Analyze complex and interacting factors that influenced the perspectives of people during different historical eras.Learning outcomesStudents will be able to explain the reasons for the westward emigration of the American population during the 1800s.Students will be able to compare the major trails.More activitiesAll US History GeoInquiriesAll GeoInquiries

Sheep (Ovis aries) were among the earliest livestock, domesticated in the Fertile Crescent about 12000-10000 years ago with a nearly worldwide distribution today. Most of our knowledge about the timing of their expansion stems from archaeological data but it is unclear how the genetic diversity of modern sheep fits with these dates. We used whole-genome sequencing data of 63 domestic breeds and their wild relatives, the Asiatic mouflon (O. gmelini), to explore the demographic history of sheep. On the global scale, our analysis revealed geographic structuring among breeds with unidirectional recent gene flow from domestics into Asiatic mouflons. We then selected four representative breeds from Spain, Morocco, the UK and Iran to build a comprehensive demographic model of the western sheep expansion. We inferred a single domestication event around 9,000 years ago, slightly later than archaeological evidence suggests which might reflect uncertainties in the generation time used for these estimates. The westward expansion is dated to approximately 5,000 years ago, later than the original Neolithic expansion of sheep and approximately matching the Secondary Product Revolution associated with woolly sheep. We see some signals of recent gene flow from an ancestral population into southern European breeds which could reflect admixture with feral European mouflon. Furthermore, our results indicate that many breeds experienced a reduction of their effective population size during the last centuries, probably associated with the breed development. Our study provides insights into the complex demographic history of western Eurasian sheep, highlighting interactions between breeds and their wild counterparts.