What was the name of the 1862 law ("act") that offered 160 acres to adult males who were willing to live on the land for 5 years and make "improvements" to it?

This is known as the Homestead Act .

During 1862, individuals were offered 160 acres of free land that they can use to start their own farm. This program created by the federal government gave away roughly 270 million acres of land. Most of this land was west of the Mississippi River. This act helped in changing the population of the Midwest United States.