The distribution of Congressional seats in Pennsylvania seems remarkable similar to that in Georgia. There is a defacto alliance in the state legislature to draw up districts in which there are three safe districts for black Democrats and eight safe districts for white Republicans.
The racial aspect is, perhaps, less explicit in PA; I know that at least in the South, there is judicial pressure to assure black representation in Congress - which, as you suggest, is mighty convenient for the black Democrat politicians and for the (white) Republican ones.