Sometimes it’s the little things that tell the larger story, like the sign about 40 yards from the security checkpoint at Reagan National Airport.

“Not much longer,” it cheerfully tells passengers as they snake toward the Transportation Security Administration scanners. “25 min approximately from this point.”

A lot of people get to see that sign — more than ever before — as Washington’s tiniest commercial airport is morphing into something it has never been and was never intended to become.

Squeezed by the Potomac River on one side and Arlington County on the other, National has endured for six decades as a destination airport: Fly in, fly home. Now, with no room for growth, it is growing nonetheless, becoming a mini-hub airport for an airline industry that has been transformed into a transcontinental network of hubs.

The new role as transit point has meant larger planes, more passengers and tons of additional luggage. Added to that, its most regular passengers — members of Congress — have insisted on new flights to the more distant cities that some of them call home.

“It’s a dramatic increase in passengers,” said Paul Malandrino Jr., the airport’s manager, as he breezed through the concourse this past week. “As an airport manager, that’s a good problem, but it’s a problem.”

It’s a good problem because the Metropolitan Washington Airports Authority runs Reagan National and Dulles International off proceeds from the airlines and airport concessions. It becomes a bad problem if passenger frustration grows while Malandrino’s team rushes to make “Band-Aid” fixes and calculates how best to achieve and pay for what is really needed.

In July, there were 75,465 more passengers passing through than in the same month in 2011. Last year, before many of the new flights were added, the passenger load increased by 704,381 over 2010. That has put the squeeze on baggage handling, parking, security and simply managing passenger flow.

Take one example: Virtually every modern hub airport is configured to let arriving passengers reach gates for connecting flights without going through security again.

As a destination airport, National never needed that web of connecting walkways on the secure side of the checkpoints. So, when more than 40 percent of arriving US Airways passengers began heading for connecting flights (a recent increase from 18 percent), the airline started offloading those people directly from the plane onto a bus that carried them to their flights in an adjoining concourse.

This is inconvenient and it’s not pretty in the rain or snow, but the alternative is sending them into the main concourse for another trip through a “Not much longer” security line before boarding flight No. 2.

With overall passenger numbers at National setting a record this summer, those checkpoints have become choke points during the busiest times. One of those peak-load hours is a subtext to the narrative that makes National unique — when Congress goes home for the weekend on Thursday afternoon, the place is mobbed. And unless they are traveling with a security detail, your senators and representatives stand in line like everybody else.