Orders started streaming in at Da Vinci's Florist & Lighting in Silver Spring in the months following the legalization of same-sex marriage in the District last March.

The store's wedding department manager, Diana Skenderovic, began marketing to couples on GayWeddings.com, after attending the city's first gay and lesbian wedding expo that May, and quickly saw results. This year, she said, is shaping up even better than the last. Business from same-sex couples is up nearly 40 percent.

Da Vinci's is among a number of local wedding vendors to have witnessed an increase in business since the District legalized gay marriage, supporting predictions that the law would benefit the region's economy.

“There seems to be some windfall for our small businesses engaged in the event and wedding industry,” said Jeffrey D. Richardson, director of the D.C. Mayor's Office of Gay, Lesbian, Bisexual and Transgender Affairs. “There is potential for a real long-term economic impact.”

A 2009 study by the nonprofit Williams Institute projected that the Washington region would rack up more than $52.2 million in revenue over three years. None of the jurisdictions in the Washington area, however, is tracking the current business impact.

Kathryn Hamm, president of GayWeddings.com in Arlington, said increased Web traffic to District vendors last year helped make the city one of the top markets on the her company's site. Hamm pointed out, however, that Virginia was the fifth most visited market, while Maryland was the 10th, a sign, she said, of the broader economic benefit of the law.

“There is opportunity out there for thoughtful vendors, who look at what their business objectives are and what the opportunity is in specific markets,” she said. “This region is exciting because it's so diverse.”

The number of vendors from the region on GayWeddings.com, one of the largest such directories in the country, has also grown tremendously in the past year. Hamm witnessed a 35 percent increase in D.C. businesses, a 28 percent uptick from Maryland companies and a 24 percent jump in vendors from Virginia.

Aside from Web sites courting the gay couples, a crop of wedding expos has sprung up within the past year to help caterers, deejays and photographers get a slice of the pie. Just this past weekend, the Washington Court Hotel hosted an expo for Marry Me in D.C., a local organization run by wedding officiants.

“Most of the vendors I've spoken to really want to work with same-sex couples but don't know how to reach the community,” said Deborah Cummings-Thomas, co-founder of Marry Me in D.C. “The expo allows them face time with couples.”

Weddings are certainly a profitable business. The average heterosexual wedding in the United States cost $24,066 in 2010, according to industry research firm the Wedding Report. While there is no equivalent data for same-sex weddings, the Williams Institute study reported that gay couples in Massachusetts spent an average $7,400.

Skenderovic says Da Vinci's has provided services for various sizes of same-sex weddings, though most of them have been smaller ceremonies of under 100 people.

Innkeeper Sandra Gartrell has found that size to be a perfect fit for Intown Uptown Inn in the District, which has played host to some 20 same-sex weddings in the past year, many with fewer than 40 people.

“Many couples bring those that are closest to them, especially when they're from out of town,” Gartrell said. “This has been a great added revenue source.”