The Homestead Act, signed into law in 1862, significantly impacted American history by facilitating westward expansion and settlement. It provided 160 acres of public land to settlers, requiring them to cultivate and improve the land for five years. This act encouraged many to migrate westward, fueling population growth in states like Nebraska and Kansas. It played a crucial role in shaping the American frontier by promoting agricultural development and the notion of manifest destiny. However, it also contributed to the displacement and hardship faced by Indigenous peoples and created environmental challenges as settlers transformed the landscape.