WASHINGTON — They came to an opening night beer blast at the National Air and Space Museum, 4,000 strong in baseball caps and T-shirts, to look at the Wright Brothers’ airplane and drink Citizen by DC Brau, which also makes a wryly named hometown brew, Corruption.

Craft beer brewers marched on Washington this week for their industry’s first conference in the nation’s capital. They were there to engage in a local pastime that goes pint in hand with drinking: lobbying. As part of the conference, hundreds of small-scale brewers met with Congressional staff members to press for a tax cut that they say would make it easier for them to brew more beer and hire more workers.

“For every 31 gallons that we brew, $7 goes to Uncle Sam,” said Jeff Hancock, a co-founder of DC Brau, one of five craft breweries that have opened in the District of Columbia and its close suburbs in the last two years, joining dozens more in the rest of Virginia and Maryland.

Washington is just one of many places where craft brewing is booming.

“We are the victims of our own success,” said Patrick Conway, owner of the Great Lakes Brewing Company in Cleveland. Mr. Conway brought a delegation of 12 employees to Washington to network and publicize his brews with tap takeovers at local bars. “We’re always being courted by distributors,” he said. “It’s not our intention to sell in every state, but we are flattered.”