What contributed most to rapid westward expansion after the Mississippi in the late 19th c.?

While steamboats played a crucial role in navigating rivers and transporting goods and passengers, their impact was largely limited to waterways. They primarily aided travel on the Mississippi River and its tributaries, which, although important, did not match the extensive reach and speed provided by railroads for land travel across the continent.

Canals were significant in early transportation, connecting rivers and facilitating trade in the 19th century. However, their capacity to promote westward expansion was limited compared to railroads. Canals required considerable time and labor to construct, and once railroads became widespread, they quickly eclipsed canals in efficiency and usability for long-distance travel.

Turnpikes, or toll roads, facilitated overland travel and trade but were limited in scope and capacity. They did not provide the same level of efficiency or speed as railroads, making them less effective in promoting the large-scale migration and economic expansion seen in the late 19th century.