Republicans started this key battle in the states but they should beware the backlash

When the Indiana state Senate recently rejected a mid-cycle partisan redistricting of its congressional delegation, it was not only a rebuke to President Donald J. Trump. It also upheld a norm that has guided American democracy for more than a century.

Since the early 1900s, states have almost never redrawn congressional maps outside the decennial census, except to comply with court orders or to make minor technical corrections. That restraint has served an important stabilizing function.