Hello, black Catholic here.
I am a life-long Catholic, and my parents are Catholic, and came from a country that is largely Hindu, due to the large east Indian population. I attended a major Catholic university, and have attended, and volunteered in, a large number of parishes.
My childhood parish was/is very diverse, with a substantial black population, a substantial hispanic population, a substantial white population, and a visible Asian population. There was a Spanish Mass, as well as a Creole Mass for the Haitian population. I attended the regular English Mass, which was representative of the town we lived in. It was literally a slice of the town. Our main parish priest was Indian (he’s still there). The nun I worked with while helping out with catechism classes was white. There was never an issue of race, and the thought never crossed my mind, nor did I ever think “wow, this is really diverse”, until now that I’m writing this. It was just how it was, and very “catholic”, as it should be.
People choose their parish for a number of reasons. A large percentage of Catholics in the USA are immigrants. Eastern Orthodox also experience this phenomenon. In immigration, people tend to go to places where their culture has decent representation, for a number of reasons. Therefore, in cities especially, it is not surprising to find parishes with a large Haitian population, a large Irish population, a large Mexican population, a large Ethiopian population, etc. In these sorts of parishes, there will usually be ceremonies in English, as well as the native language of the major population(s). Many times, they will also have cultural dances, feasts, and other activities tailored to the major population. There is nothing wrong with attending an American/Western type parish, and no one is discriminated. I certainly never experienced anything of the sort in my life as a black Catholic. All of the parishes I have attended have been very welcoming, and going to a 70+% white university was not a big deal, and I had a wonderful experience that I will never forget. Because the school was mostly white, the parish I attended (on campus) was mostly white, and again, no issue. I also attended another parish once in a while nearby, which was again mostly white (this was the sort of neighborhood the school is in), and every visitor, including myself, was warmly welcomed. I love being Catholic, and I love that there are so many types of people in our 1 billion member Church. I have never experienced discrimination in the Church, nor have I experienced or noticed self-segregation for some nefarious reason. As my parents are immigrants, I can understand the need to form cultural parishes, to maintain your cultural identity (and pass it on to your children), and even then, all are always welcome, and many types of people will come and see.
And not only are there cultural/immigrant parishes, as well as the typical American parish (usually one parish will simply cater to everyone), there are also the “particular churches”, such as the Ukrainian Catholic Church, the Ethiopian Catholic Church, Coptic Catholic Church (Egyptian), Melkite Catholic Church (Arabic), etc. In the parishes of these churches of the Catholic Church, you’ll not only find an “ethnic” parish, but they will also have liturgies specific to those churches, i.e. the Divine Liturgy. The Divine Liturgy in each of these churches will usually have some cultural peculiarities specific to that church, especially language and hymn style.