Actually, both cities are about 40% Black and while Rochester is more white collar, there were and to a degree now, manufacturing jobs in Rochester. There are also Black people that worked in white collar jobs in both areas. Both metros are about 13% Black, which is the national percentage.
Also, Black people have been in both areas for centuries due to various circumstances. If you are interested, you can look at this:
African American History of Western New York
There is also thread explaining this on this forum. Just look below.