Final answer:
The large-scale transformation of the West's landscape and economy began with the passage of the Homestead Act in 1862, which promoted the growth of communities and agriculture in the region, resulting in significant westward migration.
Step-by-step explanation:
The federal government began the large-scale transformation of the West's landscape and economy with the passage of the Homestead Act in 1862. This legislation allowed any U.S. citizen or intended citizen to claim up to 160 acres of federally owned land. The purpose of the Homestead Act was to encourage the growth of communities and the expansion of agriculture in the West, drastically changing the region's economy and landscape. It resulted in significant migration westward, altering the demographic and cultural composition of these areas.
Learn more about Homestead Act