Gerrymandering is not a Republican thing.
It's done by either party who is in control after each census.
Look what Democrats did in Maryland.
Particularly the third district. What shape is that?
And the 1st, 2nd, 5th and 7th all border it as they intertwine to make each district a Democrat majority.
Only the shore side 1st district has a Republican representative.
The largely drawn 6th district, mostly in the rural west, has a enough of Baltimore county in it to have a Democrat representative.
3/8 of Maryland's districts run through Baltimore city while 2 more touch Baltimore County.
2 more districts border DC and the 8th district almost borders DC.
7/8 House members are Democrats as are both Senators.
But the current governor is actually Republican.
http://planning.maryland.gov/PDF/OurProducts/Redistrict/CongDist/District/Color_Map/2002CongDistNoRoads.jpg
Republicans do have more favorable gerrymandering though out the country (like Ohio).
Bu the practice is bipartisan.