by Benjamin Landy, @Ben_Landy

Policy Associate, The Century Foundation, @tcfdotorg

Despite broad support from the American public, the bipartisan Manchin-Toomey amendment to extend background checks died in the Senate, six ‘ayes’ short of the 60 votes needed to overcome a Republican filibuster. But party divisions were only one reason why the gun vote failed. More important was the institutional structure of the Senate itself, which by its very design (two senators per state) gives disproportionate representation and political power to small populations in large, rural states.

If you re-adjust the map of the United States to reflect states’ actual populations, it becomes clearer that gun control legislation was defeated not only by a minority of senators, but also by an undemocratic minority of Americans.

“Of the senators from the 25 largest states, the Manchin-Toomey legislation received 33 aye votes and 17 nay votes — an almost 2:1 margin,” notes Wonkblog‘s Ezra Klein. “But of the senators from the 25 smallest states, it received only 21 aye votes and 29 nay votes.”

It’s typical to say that this is how the Senate’s always been. It’s also wrong. The filibuster didn’t emerge until decades after the first Congress, and its constant use is a thoroughly modern development.

As for the small state bias, that, too, has changed over time. During the first Congress, Virginia, the largest state, was roughly 12 times the size of Delaware, which was, at the time, the smallest state. Today, California is 66 times the size of Wyoming. That makes the Senate five times less proportionate today than it was at the founding.

Jonathan Cohn and Eric Kingsbury, writing at the New Republic, were also struck by how little the Senate vote reflected public polling, which in previous weeks showed that as many as 90 percent of Americans support background checks:

If you assume, for sake of argument, each senator represents half of his or her state’s population, then senators voting for the bill represented about 194 million people, while the senators voting against the bill represented about 118 million people. That’s getting close to a two-thirds majority in favor of the measure.

In a legislative body that didn’t give sparsely populated rural states the same representation as densely populated urban ones—and in which a minority of representatives lacked the power to block debate indefinitely—those kinds of numbers would be more than enough to pass something like the background check proposal.

This sort of political calculus is complicated, of course, by the influence of the National Rifle Association, which spent about $7.5 million on outside campaign spending during the 2012 election cycle — 99.6 percent of which went towards either supporting Republican candidates or defeating Democrats. That’s in addition to the $3 million the NRA paid to flood Congress with gun rights lobbyists.

Unfortunately, money is speech in Washington as elsewhere in the United States, and the NRA is a particularly loud voice — despite representing only about one percent of Americans. For many of the senators facing tough re-election campaigns in 2014, that alone was enough.