What was the general American attitude toward access to Indian lands and what events of the 1820–40s reveal that attitude?

American (referring to white) attitudes toward Native American land were shaped early in the history of European settlement here. The key issue was always access to land. As European settlement grew in the 17th century, known as the Great Migration, European desire for land grew as they began to push further inland. This sparked significant conflicts in the early and mid-17th century, such as the Powhatan, Pequot, and King Phillip's Wars. As the United States achieved independence and began to develop its own national policies in the 1780s, westward expansion was a major focus, and thus an Indian policy developed consisting of making treaties with Native Americans for access to their land while simultaneously pushing them further west through force.
By the 19th century, westward expansion was well underway with the 1803 Louisiana Purchase, in which the United States gained access to land west of the Mississippi river. As the country began to develop a national economic policy to incorporate this land, treaties with Native Americans were crucial to fostering white settlement in this area. The initial goal was to form treaties to ensure white settlement was a peaceful process. However, many Native American groups resisted white encroachment, such as Tecumseh's "pan-Indian" policy during the War of 1812.
A climax in these conflicts came with the presidency of Andrew Jackson (1828–36). Jackson had built a military career partly around brutal conflicts with Native Americans around the time of the War of 1812. In his presidency, he adopted the policy of forced removal of Native Americans living east of the Mississippi River. The most important event came with the Indian Removal Act of 1830. Whites had long coveted the land in northern Georgia and surrounding states, an area traditionally occupied by Native American groups such as the Cherokee and Creek. The Cherokee were unique in that they were one of the Native American groups to acculturate into white society by adopting writing, Christianity, and economic practices such as private land ownership and even, in some cases, slavery. Regardless, Jackson supported the Removal Act which would forcibly remove the Cherokee and other groups from this land. Jackson ordered the Cherokee forcibly removed from the land, under military escort, to Indian reservations in Oklahoma territory. The removal began with the Creek removal in 1836. The most dramatic removal occurred in 1838 when the US army forced the remaining 16,000 Cherokee to leave Georgia. Due to harsh weather and a lack of resources, 5,000 Cherokee died on the journey, which became known as the Trail of Tears.
The US government's pattern, throughout the 19th century, of making treaties with Native Americans and then subsequently breaking them, often with the use of force, was chronicled in Helen Hunt Jackson's book A Century of Dishonor published in 1881.