The "First" Indian Border (1763)
The British defeated the French in the French and Indian war (1754-1763). As a result France, in the Treaty of Paris (1763), gave up all claims to land in North America. The British, to protect Indian lands, implemented the famous "Proclamation of 1763" . This International Proclamation decreed that all land west of the Appalachian Mountains belonged to the Indians. To help maintain a military to enforce the Appalachian border, the British imposed taxes on wealthy businessmen landlords, and moneyed elites. However, many Eastern landlords (including George Washington, a famous "surveyor" of Indian land) "owned" much land in the west. They refused to give up this land. "Taxation without Representation" was the famous outcry. (Not much was said about the grinding taxes, fees, and fines put on the poor by local governments, landlords and the moneyed elites). Independence was declared on July 4, 1776. The Revolutionary War was fought and won. The British retreated to Canada. The Proclamation of 1763 was nullified.
The Next Indian Border - The Greenville Line (1794-1812)
Settlers and land speculators could now go west of the Appalachians and seize more Indian land without British interference. Obviously, the Eastern "landlords" and George Washington kept their large land holdings west of the Appalachians.
However, the war was not over for the Indians. They still resisted the settlers moving onto their treaty lands west of the Appalachians. So President Washington had to initiate the Northwest Indian War (1791-1794), a "scorched earth" campaign to "ethnically cleanse" the Indians from all their land in present day Ohio, western Pennsylvania, southern Michigan and eastern Indiana.
The Indian nations were defeated in a battle at Fallen Timbers (present day Toledo, Ohio) in 1794. The resulting Greenville Treaty established an official Indian border (Greenville Line) through Indiana territory. West of the line belonged to the Indians. The value of George Washington's western land holdings increased by 50%. He was arguably the richest man in the United States.
[At this point it should be noted that in 1779 during the Revolutionary War, General Washington sent General John Sullivan and 5000 troops to destroy the large Haudenosee (Iroquois) Nation. They were the "guardians of the western border" against settler expansion. They were also the first democracy in North America. Parts of the U.S. Constitution were modeled after them. The army destroyed all the villages, orchards, and crops throughout middle and western New York. Many Iroquois died that winter. (These deaths are hardly ever mentioned as Revolutionary War casualties). The Iroquois never recovered from this. George Washington became known to the Indians as "Town Destroyer".]
The Indians Nations, under the leadership of Tecumseh, started building an "Indian capital" at Tippecanoe, Indiana to control and defend the Indian lands west of the Greenville Line. However, in 1811 General William Henry Harrison crossed the Greenville Line, destroyed the capital, and broke up the Indian alliances. In the following War of 1812 many battles were against the Indians.
After the War of 1812, the Indians lost the protection of the British. Settlers, real estate agents, family farmers, lumber industries, landlords, and land speculators were now free to pour into Indian Lands west of the Greenville Border.
The Next Border - The Mississippi River (1830-1850)
The Indians still resisted. So, in 1830 President Andrew Jackson wrote and Congress passed into law the Indian Removal Act. This "ethnic cleansing" act or "final solution" to the Eastern Indian Problem was to remove most eastern Indian populations to west of the Mississippi. This act authorized the President to break, rewrite, or issue new treaties to accomplish this. It also funded the US Army to carry out the removal. By 1850 over 60 Indian nations were removed "west" and over 100 treaties were broken, rewritten, or re-issued.
For example, In 1837 the Santee Sioux and Winnebagos (Ho Chunks) living in Wisconsin were each issued Treaties. The treaties ordered them to cede all their land in Wisconsin and remove to West of the Mississippi. The Ho-Chunks, once occupants of present day Vernon County, were removed to Northeastern Iowa. In 1846 while Moses Decker was "axing" his way through the wilderness to found present day Viroqua, the Ho-chunks were being further removed from Iowa to Minnesota.
Moving The Mexican Border (1846-1848)
In 1846-1848 the United States invaded Mexico and took half of Mexico from the Mexican People. This land became present day California, Colorado, New Mexico, Arizona, Utah, Nevada, parts of Oklahoma, and Kansas). Obviously, many Indians lived on these lands and had to be "dealt" with.
The Next Border - the Reservation Borders
Settlers, family farmers, and land speculators kept pouring onto Indian lands west of the Mississippi (including the newly acquired Mexican lands). The Indians resisted them.
President Abraham Lincoln, never a friend to the Indians, continued, provoked, or initiated several wars against the Western Indians. He also continued the policy of Indian Removal and land theft. By 1877 the Western Indians were "subdued" by overwhelming military force and countless massacres. (Although subdued, Indian Nations to this day have heroically worked to get their lands back, and to run their own affairs as sovereign nations).
Crossing the Reservation Borders (1887-1934)
By 1887 the tribal lands defined by many treaties had been reduced to 150 million acres. The new border(s) were now the borders of the many "Indian Reservations".
However, settlers, family farmers, and land speculators wanted their share of the reservations. So, in 1887 Congress passed the General Allotment Act (Dawes Act). This "Land Grab" Act said that reservations had to be broken up into 40, 80, or 160 acre sections and each section had to be "owned" by an individual Indian. Tribally owned land became illegal. Any excess reservation land was sold by the US government to white settlers, family farmers, or land speculators. Although defined as "sovereign nations" under Article 1 Section 8 Clause c of the US Constitution, the Indians were no longer allowed to have their own tribal government. They were to be ruled under the dictatorship of Bureau of Indian Affairs (BIA).
The Dawes and subsequent acts stated that as Indians became "competent" they could sell their land allotments to Whites. (They were considered competent when they signed many treaties). By 1934 over 100 million of the 150 million acres of Indian Land was sold or lost to family farmers, settlers, real estate agents, and land speculators. Also, many Indians could not or did not know how to pay taxes (or other expenses) on their land and their land was seized for "auction". Today, most reservations look like checkerboards.
Breaking Into the Cultural Borders (1887-1934)
Throughout this period (1887-1934) countless Indian children, many as young as six, were taken from their families and put into Indian Boarding Schools for years at a time. They were not allowed to use their Native Language, engage in Indian ways, or learn about their culture or heritage. They were being trained to be Christians and workers for America's capitalists. Also many Indian religions were outlawed by the government.
Strengthening the Reservation Borders (1934-1954)
Realizing that the Dawes Act proved disastrous for American Indians, Congress passed the Indian Reorganization Act of 1934. Tribes could now have tribal lands held in common and have their own leadership and constitutions. It now became difficult for land speculators to buy Indian land. Indian children were no longer seized and put into Boarding Schools. They could go "voluntarily."
A local example. Here in Wisconsin, the Oneida Nation originally had 5 million acres. A treaty in the 1830s reduced it to 65,000 acres west of Green Bay. By 1934 the Oneida owned less than 300 acres of their original reservation. [They have reacquired 17,000 acres of the original 65,000 acres - thanks mainly to gaming revenues]. They want to repurchase all 65,000 acres. However, the price of the land has become obscenely high.
Weakening the Borders (again) (1954-1972)
But determined land speculators, family farmers, resort owner wannabees, and vacation home people still wanted Indian land. To get the Indians off the reservations and into the cities the Eisenhower administration, in 1954, passed the Indian Relocation and Termination Act. This Act provided entry level job training to reservation Indians, and a bus ticket to "relocate" them to large cities where Indians could work while living in slums and eventually climb the ladder to "success". Also Congress could "terminate" the status of Indian Nations who were failing to thrive or were actually successful. [Note: Removal became Relocation and Extermination became Termination].
A local example. In 1964, the successful Menominees in Wisconsin had their reservation taken from them under the 1954 Act and made into a county. Their federal status as "Indians" was terminated. This proved disastrous. Land was lost, poverty levels sky rocketed, and land speculators, resort owners, and vacation home buyers moved in. This Act was repealed in 1972. The Menominee are still recovering. [Note: During this time the Menominee lost a small part of their reservation to vacation home and resort people].
There is so much more regarding borders and immigration. If some one is interested, they can start by reading Howard Zinn's book A People's History of the United States.