Who led an important expedition through the Great Plains?

Major Stephen Long is recognized for leading an important expedition through the Great Plains during the early 19th century. His exploration, conducted in 1819-1820, aimed to survey and map the region, contributing significantly to the understanding of the geography and resources of the area. Long’s expedition provided valuable information about the Great Plains and influenced future settlement and exploration patterns, making it a key event in American history.

Lewis, Sherman, and Frémont undertook notable military and exploratory missions, but their primary focuses were not specifically centered on the Great Plains in the way that Long's was. Lewis is known for his leadership role in the Lewis and Clark Expedition, which primarily explored the Pacific Northwest. Sherman is known for his role in the Civil War, and Frémont conducted several expeditions in the American West but did not focus exclusively on the Great Plains. Thus, Long's dedicated work in that region stands out as particularly significant.