The likely effect on Congress, given the demographic distribution of voters and the gerrymandered districting, is:
Congress reflects increased weighted favoring of one party despite rough parity in voter affiliation.
This conclusion is based on the fact that the districting splits the population such that all districts are dominated by one group (in this case, the White voters), leading to a lack of representation for the minority group (the Black voters). While there are more voters in total (11 White vs. 4 Black), the way the districts are drawn results in a situation where minority voices are effectively minimized within Congress, despite their overall percentage of the population.