The real problem not the ratios, they’re about 530k per rep at minimum (Rhode Island) to 995k per rep maxium, for Montana. California, Illinois, and New York are 705, 715, and 720k per rep respectively.
No, the problem is single seat districts with winner take all elections. Imagine if, for example, Austin Texas was, instead of being broken into 5 separate districts so that only 1 Dem is elected despite majority voting, it was part of two different 3 seat districts. Change nothing of the votes, yet you have two districts that, probably, have two dem representatives and one republican each. Or, for the conservatives, Cook County. No GOP reps are here, though the population is not zero. With multi distrct votes, you probably see a different outcome. Right now, of the 11 districts in the Chicago metro area, with 8 of them all, or in part, in Cook county, Of the 7 non Chicago seats, 6 are GOP. Of the 11, 1 is GOP. Changing them to multi seats probably doesn’t change the makeup of party ratios, but it does some important things here.
It means everyone can have a voice.
Right now if you live in some D or R +20 district (of which Illinois has a bunch of D >+10) then you have effectively no chance. Your vote is pointless. Single seat districts are objectively terrible.
But multi seat districts everyone has a chance to have a voice. No longer are liberals in rural areas irrelevant. Or conservatives in cities ignored. Changing things that way would go a very long way to fixing many of our problems. It would encourage less extremism, it would increase participation (in theory) by not making so many peoples votes pointless, it would also make gerrymandering much more difficult. Even the kind not done for partisan means, like the Illinois 4th. Which is done for a genuinely good reason! It is a ridiculous district drawn to give the hispanic community representation. Because, right now, with FPTP minority communities tend to get drowned out. Or get ridiculous strings connected by fields and highway shoulders simply to maintain contiguity. Drop that and have multi seat districts, and now that 30% hispanic population, or asian, or black, or whatever can get a voice by congealing around the candidate that represents them within a broader district.
It would be so much better, in so many ways. Our voting system is about the worst possible one, and is in large part responsible for the shitshow politics has become.