The way the drive for gun control got stymied shows that the operative dynamic in the Senate has become more insidious than ever.

It turns out that, in this case, the wishes of 9 in 10 Americans can be repelled by a group of lawmakers representing fewer than 3 out of every 8.

A whole series of surveys have found support in the 90 percent range for requiring background checks before almost all commercial firearms sales. That’s about as close as it gets to unanimity in the polling world. And that’s the heart of the proposal that was blocked Wednesday, effectively ending the debate over how best to reduce gun violence  — at least until after the next massacre in a schoolhouse, movie theater or supermarket parking lot.

On the surface, the reason was that 45 senators opposed the idea and, under the new normal for accomplishment in the chamber, any proposal of consequence can be stopped by any bloc of 41 or more. That’s because, three years ago, the dilatory dysfunction got so bad that the leaders of both parties struck a handshake deal. To keep filibusters from swallowing the Senate calendar whole, they would grant the minority an extra measure of leverage on any controversial votes for passing bills or adding amendments: They could insist that the other side come up with 60 affirmative votes, or a three-fifths supermajority.

The extent of that power was on profound display during the background check vote. With help from my colleague in news research, Jay Hunter, we assigned half of every state’s population to each of its senators and quickly calculated that the senators who killed the measure were voting on behalf of 37 percent of the nation’s populace. (Majority Leader Harry Reid’s “no” wasn’t counted because the Nevada Democrat only switched sides to preserve his parliamentary right to demand a do-over sometime in the next 20 months.)

Leaving out just one state and its lawmakers — the 26 million Texans who have Republicans John Cornyn and Ted Cruz as their spokesmen — the share of the national population represented by the senators on the prevailing side was 31.5 percent.

Viewed another way, 32 of the “no” votes were cast by senators from states with fewer than 5 million people, and all their states are home to just 15 percent of the population. From that group, Alabama and a dozen even smaller states — each of which has voted Republican in at least the past four presidential elections — saw both their senators oppose the compromise.

Plenty of people who did just fine in the civics portion of American history will be tempted to say: So what? This sort of outcome was guaranteed by the framers, who created a Senate where every state had equal representation, and where unfettered debate was encouraged, precisely so that the dissenting voices and the rural states would have the kind of clout they could only dream about in the House.

Yes, but …

There is no evidence the drafters of the Constitution contemplated the Senate’s tradition of unlimited debate morphing into a situation where the majority has to grow to three-fifths before it can lay claim to amending a bill. And the disparity between the big states that would surely dominate the House and the small states with a chance to exert power in the Senate is entirely different now from what it was at the end of the 18th century.

When Congress was created, Virginia was the biggest state and had 13 times the population of Delaware, then the smallest state. Today, there are 66 people in California for every one in Wyoming; 29 New Yorkers for every North Dakotan; and 17 people in Illinois for every person in Alaska.

And, accordingly, all six senators from those enormous urban and suburban states, with a combined population of 70.4 million, voted to require background checks before sales online or at gun shows. And all six from the tiny rural states, with 2 million residents among them, voted the opposite way.

To be sure, gun control legislation faltered for obvious reasons: The National Rifle Association remains as powerful and aggressive a lobbying power as ever, President Barack Obama’s personal attempts at persuasion didn’t work, three Democrats running in red states next year decided they could lose if they voted with their party, and the roster of maverick Republicans has atrophied.

But a final reason arches over all those: The system is skewed as never before to favor crusades by a determined minority from the small states. The NRA’s powers of persuasion may be without peer, but the 60-votes-for-everything Senate and the suburbanization of the nation have made its job a whole lot easier.