After the American Revolution, the United States took control of the lands that had been previously claimed by each of the colonies west of the Ohio River. In 1785, Congress passed the land Ordinance Act allowed the public domain lands to be sold for profit. When the land was sold, patents were issued to the person buying the property from the U.S. government. The land sold to the settlers form the bulk of the Eastern States Land Records held by the Bureau of Land Management. More than a billion acres of land and 7.5 million transactions are recorded in their office.
Homestead Act of 1862
The Homestead Act was signed into law by President Lincoln on May 20, 1862. This allowed any U.S. citizen or intended U.S. citizen who had not borne arms against the United States to file a claim to 160 acres of land. The homesteader had to live on the land for five years, during which he had to 'improve' the land by building a house and growing crops on the land. Due to the difficult conditions of prairie life, however, many people did not stay the full time.
The Land Policy and Management Act of 1976 repealed the Homestead Act after millions of applications had been processed for government land. (Note: The Act was extended for ten years in Alaska with the last title under the law being given in 1988.)
For those of you fond of the Little House on the Prairie books, Laura Ingalls Wilder's father Charles Ingalls and her husband Alonzo Wilder filed claims for land under the Homestead Act. NARA has an article about them on their website: Link.
You can look up land patents at the Bureau of Land Management: Link
(My 3rd great-grandfather Solomon Osborn Atchley purchased 40 acres in Indiana in 1838.)
Historical Note: Not all land west of the Ohio will have a land patent on this website. Missouri, for instance, was owned by the Spanish and French, and many people went west and got patents from those governments instead.
Bureau of Land Management. "Our Record Keeping History." http://www.glorecords.blm.gov/reference/default.aspx#id=01_GLO_Records|01_Our_Record_Keeping_History.
National Park Service. "Homestead National Monument of America." http://www.nps.gov/home/historyculture/index.htm"
NARA. "Teaching with Documents: The Homestead Act of 1862." http://www.archives.gov/education/lessons/homestead-act/.