When Larsen arrived in Washington in the early '80s, there were a just handful of Mormon meetinghouses in northern Virginia, where he lives. Today, there are more than 25, each housing three separate congregations, or wards, as they're known in the LDS Church.

"There's been an absolute explosion in Mormon growth inside the beltway," Larsen says before slipping out of the pew to crank the air conditioning for the swelling crowd.

The LDS Church says there are 13,000 active members within a 10-mile radius of Washington, though the area's Mormon temple serves a much larger population -- 148,000 Latter-day Saints, stretching from parts of South Carolina to New Jersey.

Signs of the local Mormon population boom transcend the walls of the temple and meetinghouses.

Crystal City, a Virginia neighborhood just across the Potomac River from Washington, has become so popular with young Mormons that it's known as "Little Provo," after the Utah city that's home to church-owned Brigham Young University.

Congress now counts 15 Mormon members, including Senate Majority Leader Harry Reid, according to the Pew Forum on Religion and Public Life. That means the 2% of the country that's Mormon is slightly overrepresented on Capitol Hill.

Even many Latter-day Saints joke about Washington's "Mormon mafia" -- referring to the number of well-placed LDS Church members across town -- though they cringe at the thought of being seen as part of some cabal. (Echo Hawk, for his part, left the Obama administration a few weeks after his chapel presentation for a job in the LDS Church hierarchy).

"No one talks about Washington being an Episcopalian stronghold or a Jewish stronghold," says Richard Bushman, a Mormon scholar at Columbia University. Talk of "Mormon Washington," he says, "represents a kind of surprise that people who were thought of as provincial have turned up in sophisticated power positions."

Bushman and other experts note that, despite Mormons' growing political power, the official church mostly steers clear of politics. It's hard to point to federal legislation or a White House initiative that bears distinctly Mormon fingerprints, while it's easy to do the same for other faiths.

For example, the White House's recent "compromise" on a rule that would have required religious groups to fund contraception for employees was mostly a reaction to pressure from Roman Catholic bishops.