As bad as that 63 seat loss in the House in 2010 was, it was't as bad as the epic disaster at the state level, leading to insane pro-Republican gerrymandering for the next decade.
Or possibly worse in the case if North Carolina.
NC, MN and AL were the worst in terms of strong D majorities flipping R.
I think that by "Or possibly worse in the case
of North Carolina," illegaloperation is referring to the fact that the Governor, I believe, has no veto of either Congressional or Legislative redistricting plans in North Carolina. So there's no lever of redistricting power that the Democrats can get without overcoming an existing redistricting plan that works against them. And every decade at least (I'm not sure if NC has rules against mid-decade redistricting) the Republicans get to redraw the lines, so the fact that in 20 years the existing districts might be okay for the Democrats won't matter). Basically, North Carolina will probably have a Republican Legislature and lopsided Republican U.S. House delegation for decades probably.
Whereas in other states, like Michigan, Ohio, Pennsylvania and Wisconsin, if the Democrats won the 2020 Gubernatorial election, a reasonably competitive map for both houses of the Legislature and for Congress would probably result in 2021 (competitive in terms of the contest for control of each chamber and a likely balanced congressional delegation, not in the districts, as bipartisan gerrymanders with a bunch of safe districts for each party are common in such situations), and both parties would have a shot at a trifecta during that decade and in time for the redistricting in 2031.
Of course, the NC Democrats had the huge advantage the NC Republicans have now and blew it in 2010, so they can't really complain for, depending on your point of view, a few decades or over a century. Of course, for a long time the Republicans would not have been competitive under any plan but they might have felt the "permanent box-out" for a while after they could have potentially broken through under a fair plan (although I think they took one house of the Legislature in 1994).
