I'm not a trail historian, so I will leave it to others to answer that part of your question. I can address the issue of discrimination, which they encountered in the West. First, however, it is important to understand that the West is the largest region of the continent, and it is enormously diverse, so generalizations about one place does not necessarily fit another - and time had a way of changing things as well (and not always for the better!).

Some of what African Americans found in the West depended on their numbers: they often arrived in numbers that were too few for the white majority to find them threatening.

Nineteenth-century prejudice in the West was often directed at Chinese Americans and against the Spanish-speaking communities. Native Americans, of course, received their own brand of racism and ill-treatment. It was not uncommon, consequently, for African Americans to find themselves on the "fourth rung" of the ethnic ladder, so while they may have been on the "bottom rung" in the South or elsewhere in the East, their status could be slightly and comparatively better in the West. That said, we should never discount the fact that African Americans generally faced hurtful racism and discriminatory practices both socially and legally.

There are examples of ranching families of African Americans who did very well, and they could do equally well in urban settings. Because many of the states of the Far West were fiercely in support of the North during the Civil War, many had a "spill-over" sympathy for the plight of African Americans. The play "Uncle Tom's Cabin" (based on the famous pro-abolitionist novel) was very popular in the American West, reflecting how some of this sympathy played out.

In my research area of the mining West, I found examples of African Americans being held in high regard while also being the victims of racism. In Virginia City, shortly after the Civil War, for example, Dr. W. H. C. Stephenson, an African American physician, stood in line to register to vote, which he did. But the person in line behind him refused to register saying that if a black person were allowed to register, then he didn't want to. This was a hurtful expression of racism (although it would be nice if more present-day racists took this sort of hard line and refused to vote!). At the same time, a reporter for the Territorial Enterprise, the local newspaper, wrote that it was a shame that the order of the registrants was not reversed, since the dignified African American doctor would have had the good sense to know it did not matter if he put his signature after that of an inferior (referring to the white racist) - so here we have an indication of more kindly feelings toward an African American. At the same time, the schools of Nevada were fully integrated. For information about this community, see this article.

It would be easy to find all sorts of examples of good treatment of African Americans and to cite examples of their economic and social success. It would be wrong to leave it at that and to assert that they were, therefore, free of prejudice and discrimination. Racism was a strong theme in the American West, and African Americans accomplishments were achieved while facing a stiff headwind.

During a presentation in the 1990s, I was attempting to make the case that the pro-Union nature of Nevada allowed for more generous treatment of African Americans. And that the Chinese Americans, Native Americans, and Speakers of Spanish faced much more hurtful forms of racism during the nineteenth century. Elmer Rusco, the esteemed historian of prejudice in Nevada (see his Good Times Coming?": Black Nevadans in the Nineteenth Cenury 1976), argued strenuously against what I was saying. He felt that the hurtful aspects of racism should never be diminished or soft-peddled in any way. That was not my intent - then or here at this moment. Racism is a dreadful thing and it leaves wounds that can linger for a lifetime. If we could say that the racism against African Americans in 1870 in Nevada was only a "6" while in Mississippi it was a "10" (and if it was a "10 against Chinese Americans in Nevada), it matters little: the net effect of a "6" can be just as hurtful and damaging as a "10" - whatever those numbers mean.

So in answer to your question, African Americans coming West found a milder form of discrimination, and many may have heard that they could come West and live a slightly better life free of some of the restraints of the South and East. But prejudice still existed. In addition, African Americans in the West ran the risk of being isolated in a way that could be even more hurtful.