Public domain (land)
Public domain lands are those that cannot be sold since they are considered to belong to the whole community. Public domain land is managed by a public entity like, in different countries, the State, a region, a province or a municipality, directly or by institutes or state companies. It is referred to as dominio público (Spanish), domínio público (Portuguese), domaine public (French) or demanio pubblico (Italian). Examples of public domain land are the margins of the sea and of rivers, roads, railways, ports, airports, military areas, etc..
United States of America
Public domain lands are those not under private or state ownership during the 18th and 19th centuries in the United States, as the country was expanding. These lands were obtained from the 13 original colonies, from Native American tribes, or from purchase from other countries. The domain was controlled by the federal government and sold to state and private interests through the auspices of the General Land Office. For most of the nation's early history, the government sought to promote settlement of the expanding frontier by selling off the public domain after it had been acquired. The authority for this came under laws such as the Homestead Act, the Timber and Stone Act, and the Morrill Act.
The creation of the first public domain of the United States, the Northwest Territory, began an epoch in American political history. It was decided early that new states would be created from it, to be added to the union in full equality to the original 13 states. Its subsequent expansion, the mode of its administration, legislation for its government, its relation to constitutional questions, the diplomacy and politics involved in its acquisition, its international boundary questions, the enactment of settlement laws, the attraction of immigrants and growth of population, internal improvements and increased facilities of transportation, the discovery of precious metals, and other similar topics of interest might be cited here in connection with the public domain.
During the American Revolutionary War, Congress spent all of its money and was in debt. It promised soldiers land instead of money salaries. After the revolution, the new federal government owned all the public land except that within the 13 original colonies and a few non-original states. The land owned by the government was called The Public Domain. The Land Act of 1785 gave land warrants to the soldiers to fulfill the promise. The Act also allowed the Treasury Department to sell land in auctions to the highest bidders. A new surveying system was created. The first auction was held in D.C., but the land sold was in Ohio. Soldiers could not afford to travel to Ohio to see the land, and then back to D.C. for the auction. Soldiers sold their warrants, often too cheaply. The government sold 640 acres at a time, minimum. Small farmers could not afford the prices. Speculators bought the warrants, purchased land, and sold the land in smaller lots to small farmers, at a huge profit.
Later, the government lowered the minimum acres, and sold land on credit, and offered some free land. The government made more money this way by copying the speculators' method. The government gained other land in time. States were then carved out of the public domain. The government has sold or given away over one billion acres of land. 5 million land patents were granted. The Bureau of Land Management grew from of the older General Land Office and now controls public domain land. 
- Satō, Shōsuke (1886), History of the Land Question in the United States, Baltimore: Johns Hopkins University, pp. 5–6