In the United States, where a party’s voters live matters immensely. That’s because most representatives are elected from single-member districts where the candidate with the most votes wins, as opposed to a system of proportional representation, as some democracies have.
Democrats tend to be concentrated in cities and Republicans to be more spread out across suburbs and rural areas. The distribution of all of the precincts in the 2016 election shows that while many tilt heavily Democratic, fewer lean as far in the other direction.
As a result, Democrats have overwhelming power to elect representatives in a relatively small number of districts — whether for state house seats, the State Senate or Congress — while Republicans have at least enough power to elect representatives in a larger number of districts.
Republicans, in short, are more efficiently distributed in a system that rewards spreading voters across space.
This helps explain why Republicans have controlled the Pennsylvania State Senate for nearly four decades, despite losing statewide votes about half that time. It explains why Republicans are routinely overrepresented in state legislatures, even in blue states like New York. It explains why Hillary Clinton carried only three of eight congressional districts in Minnesota — districts drawn by a panel of judges — even as she won the whole state.
In most European democracies, geography doesn’t matter in the same way. Legislators are elected from larger districts, each with multiple representatives, granting parties proportional power. If a party wins 50 percent of the votes, it doesn’t matter much if those votes are evenly spread around or tightly clustered.
Britain, Australia and Canada, unlike much of Europe, have the same majoritarian system the United States does, and urban-rural divides appear there, too.
Underrepresentation of the left, Mr. Rodden argues, is a feature of any democracy that draws winner-take-all districts atop a map where the left is concentrated in cities.