I was looking over this map of the 1860 presidential election, and I was surprised by how many counties voted for Breckinridge out on the west coast. I then looked at the actual returns, and I was surprised to find that Breckinridge only had a few thousand fewer votes than Lincoln and Douglas respectively. I had always thought that support to Breckinridge was confined to the deep south and some border states, so why did such a high percentage vote for him in California and Oregon?
There was a substantial population of pro-slavery "Lecompton Democrats" in California. In 1859, their candidate, Milton Latham, had won the gubernatorial election with nearly 60% of the vote. Latham was himself, not surprisingly, a Breckinridge supporter.
The question then arises why California turned away from Breckinridge in the 1860 presidential election. The pre-existing split in the state Democratic party was exarcerbated by two factors:
In addition, the Republican platform of 1860 included an explicit commitment of a transcontinental railroad to the Pacific, which would obviously be of huge benefit to the state
Source: Hittell, History of California, volume 4
