When did the US pioneers start and end?

The era of U.S. westward expansion, often referred to as the pioneer movement, began in the early 19th century, around the 1820s, and continued until the late 1800s, with significant milestones such as the Oregon Trail (1840s) and the California Gold Rush (1848-1855). The closing of the frontier is commonly marked around 1890 when the U.S. Census Bureau declared that the American frontier was no longer a distinct line. This period was characterized by the migration of settlers into the American West in search of land, opportunity, and a new life.