NY State Senate
It seems that a couple of days ago the Republican Party's majority in the New York State Senate got cut to just one seat. The significance of this may escape non-locals, but the basic deal is that the New York legislature is horribly gerrymandered so as to make it very, very, very difficult for Democrats to get a majority in the State Senate even though it's a very Democratic state. This state of affairs is part of a tawdry implicit bargain between the Democratic Assembly leader and the Republican Senate leader, whereby the two of them essentially rule the state through backdoor deals irrespective of public opinion and the outcome of gubernatorial elections.
Meanwhile, it has the effect of giving the Republicans a big say in the congressional districting process in a heavily Democratic state. Given the underlying distribution of actual voters in the state, were the Democrats to seize control of the Senate district boundaries would be drawn to produce a couple of new House Democrats plus the State Senate lines would be redone in such a way as to make a GOP comeback unlikely.