it was an act of congress to encourage people to move to the west and get abut 160 acres of free land but you had to do something with it.
Oregon territory 1846
President Jefferson wanted to buy a port in New Orleans. France needed money so they sold them the whole Louisiana purchase through a treaty. it cost them 15 million.
texas annexation 1845
It was the peace treaty of Guadalupe hidalgo it officially ended the Mexican-American war. It defined the Mexican cession. they gave up upper California and New Mexico.
transcontinental railroad / Gadsden purchase
the Oregon dispute between the U.S. and Britain was settled by signing the Oregon treaty,
Texas was added to the U.S. because they scared that the Mexicans would want there land back so we annexed into the U.S.
The Gadsen purchase included lands in the south of the Gila River and west of the Rio Grande where the U.S. wanted to build the transcontinental railroad. The railroad was used revolutionize transport in the U.S.