The primary purpose of the Homestead Act, signed into law in 1862, was to encourage westward expansion in the United States by granting 160 acres of public land to any adult citizen or intended citizen who was willing to pay a small fee and improve the land by building a dwelling and cultivating crops. This incentivized settlement in the West, aiming to promote agriculture and economic development. The act played a crucial role in populating the Great Plains and shaping American society, although it also led to significant displacement of Native American tribes and contributed to conflicts over land use and ownership.