During the period from 1820 to 1860, there was great expansion of the United States territory. Some strongly believed that slavery was the only cause of this growth. Opponents of the annexation of Texas and the Mexican war were the main supporters of this belief because they so strongly opposed the addition of a new slave state. Other factors, however, influenced the expansion that occurred during this time. These include the emigrants that were moving to Oregon, those who wanted to take California from Mexico, and those that wanted San Francisco itself.
"After twenty-five years, the American population has begun to extend itself to the Oregon territory. Some hundreds went a few years ago; a thousand went last year; two thousand are now setting out from the frontier of Missouri; tens of thousands are mediating the adventure." (A) Most of the people in the Oregon territory were fur traders; this land benefited their needs to gain furs to sell and trade. During the 1820s, the population grew dramatically because missionaries pointed to this territory as a place for evangelical efforts. The population of this area was not merely interested in the land in order to further slavery.
In addition to the Oregon territory, the area of California was a target for expansion as well. It is also true that people did move farther west in order to expand, not necessarily for another purpose except to expand. "California, will probably, next fall away from [Mexico] The Anglo-Saxon foot is already on its borders." (D).
Again, California is the target for the potential growth of the nation. The reasoning is not to further slavery. The harbor contained in San Francisco, however, drew attention to the area. "We ought to have the Bay of San Francisco. Why? Because it is the best harbor on the Pacific!" (E) Though there are many reasons behind the growth, it is not right to say slavery is excluded as a factor.
