There WAS an African American colony; other comments re: U.S. destiny
Well - just to throw this in - the U.S. actually did have something of an African colony, Liberia. Although it wasn't an official colony, it was a group of Americans who created a country in Africa that has remained - to this day - closely affiliated with its mother country. True, these Americans were of African descent, but the vast majority of their ancestors had been in North America for more than 3 generations. So the possibility of other African colonies is not that remote, especially if that ridiculous notion of "African colonization" (where the African-American population was removed "back" to Africa) ever got more off the ground.
As for the Pacific, as early as the 1810s the U.S. was trading heavily in the major ports of the Pacific, and a fair number of Americans were settling in places like Hawaii, where, as early as the 1820s, they would soon be a major cultural factor. Now, whether the U.S. would have made these places outright colonies before they actually did is debatable, but it is plausible that de-facto colonies would have existed then.
Finally, for most Americans (and here I mean "citizens of the United States," rather than those "other" Americans, the citizens of Mexico or Canada), the idea that the West (i.e., Mexican North America) "belonged" to them through "Manifest Destiny" was one that only really existed after the mid-1840s, and even then only among a minority of people. For most Americans, the lands of California or New Mexico were exotic, far-away places: after all, they didn't even speak English there! It was only when large numbers of U.S. citizens flooded into California during the Gold Rush that California came to be seen to be as much an "American" place as "Mexican." Despite that, though, (as was noted in an earlier post), there was a vocal antiwar movement that argued that the U.S.'s seizure of half of Mexico during Mr. Polk's War was illegal and immoral. Many in the antislavery movement saw that seizure as merely a grab for more territory for slavery (which subsequent events may have proved true).
Finally, Mexico was undergoing some deep structural problems in 1836 (relating mainly to political stability; Santa Anna himself was certainly a significant factor) that continued through to the end of the Mexican-American War. If these factors had been a bit different - Mexico was, and remains, a potentially rich country - then the Mexicans could have won the 1836 war against Texas or, later, the United States. It's mere arrogance to assume that either of those outcomes were destined to be.
So - in fact, although the "60% of Africa" eventuality is an extremely unlikely (historically speaking) event, some sort of colonization of Africa is possible. Likewise, some sort of Pacific colony. Likewise, no U.S. conquest of the American West. None of these things are written in stone, and I have to respect any game that allows them to happen. (Within reason, of course
