How Democrats learned to stop worrying and love the gerrymander

The grinding battle over congressional redistricting is drawing to a close. And, contrary to expectations that the process would result in big Republican gains, the final House of Representatives map may well improve somewhat for Democrats.

The main reason is gerrymandering — redrawing of district lines for partisan benefit. Republicans built on their existing gerrymanders to try to expand their House advantage, but Democrats fired back even more powerfully with gerrymanders of their own.

Basically, Democrats saved themselves by resorting to a tactic they’ve previously denounced as not only unfair but downright...