Several readers make a very good point I confess I had not fully considered: The electoral college. If you expand the House you give the House more electoral votes. As this reader points out:

Republicans would face a hard time ever electing a President, as the 2 electoral votes per Senator would be seriously diluted. A proportional increase in the Senate might mitigate this, but if you thought California’s 56 or thereabouts EVs were troubling, how about them having over 150?

It’s a good point, and certainly one that should make the idea more attractive to liberals eager to give urban centers more political clout. I have some thoughts, but I think I’ll ponder it more first.