Territorial gains during the early nineteenth century, helped America economically through cheaper land and more workers, but lead to disagreement and tension over the Missouri Compromise and how it should be handled in regards to Texas.
The Florida and Oregon purchase, helped fishers, and the coastal workers respectively. Along the Pacific coast there was somewhat of a boom thanks to new territorial acquisitions. But things took a turn for the worst. Thanks to the Land Act of 1820, which made land significantly cheaper, immigrants could come over and work the land. This lead to a demand for more land, and the question over whether Mexican land should be used for slavery, which the South felt was their right under the Missouri Compromise. The 36-30 line called for all land North incl. the Lousiana Purchase-of this line to abolish slavery/prohibit it. But it became a fight over Texas annexation, and those who wanted Texas for slave land, versus those who wanted to keep Texas as an independent Republic. This state-gov/slave vs. non-slave fight increased pre-Civil War tension.