This imbalance is partly by design.
The greatest and the smallest states each have two senators,
in order that Congress should represent territory as well as people.
Yet the over-representation of rural America was not supposed to affect the House and the presidency.
For most of the past 200 years, when rural, urban and suburban interests were scattered between the parties, it did not.
Today, however, the 13 states where people live closest together have 121 Democratic House members and 73 Republican ones,
whereas the rest have 163 Republicans and just 72 Democrats.
America has one party built on territory and another built on people.
The bias is deepening.
Every president who took office in the 20th century did so having won the popular vote.
In two of the five elections for 21st century presidents, the minority won the electoral college.
By having elected politicians appoint federal judges,
the American system embeds this rural bias in the courts as well.
If Brett Kavanaugh, whom President Donald Trump nominated this week, joins the Supreme Court,
a conservative court established by a president and Senate who were elected with less than half the two-party vote may end up litigating the fairness of the voting system.
This bias is a dangerous new twist in the tribalism and political dysfunction that is poisoning politics in Washington.
Americans often say such partisanship is bad for their country
(and that the other lot should mend their ways).
The Founding Fathers would have agreed.
George Washington warned that "the alternate domination of one faction over another, sharpened by the spirit of revenge…is itself a frightful despotism".
As a component of partisanship, the built-in bias is obviously bad for Democrats.
But in the long run it is bad for America as a whole, including Republicans.
When lawmaking is paralysed, important work, such as immigration and entitlement reform, is too hard.
The few big laws that are approved, like Barack Obama's health-care reform or Mr Trump's corporate tax cuts, pass on party-line votes.
That emboldens the opposition to reverse or neuter them when they take power.
Meanwhile, the task of resolving the most divisive political issues often falls to the courts.
The battle over Mr Kavanaugh's confirmation will be a proxy war over issues, like abortion and health insurance, better suited to the legislature.