In Pennsylvania, backers of same-sex marriage say people who don't like the idea would at least like this:

Millions of dollars in new revenue that would flow from taxes and fees, and the millions more in new spending at wedding-related businesses across the state.

"What Pennsylvanians need to clearly understand," said Ted Martin, executive director of Equality Pennsylvania, a gay-advocacy group, "is that by being so insular, by being so provincial, we are losing money."

While the Corbett administration prepares to defend the state ban on gay marriage in court - without help from Attorney General Kathleen Kane, who says she can't ethically support the prohibition - other states gain.

In New York City, officials say the first full year of legal same-sex marriage brought $16 million in direct revenue to the city, among $259 million in economic impact for hotels, restaurants, caterers, and wedding suppliers.

The 8,200 same-sex marriage licenses issued between July 2011 and 2012 represented more than 10 percent of 75,000 total licenses. For those gay weddings, 200,000 guests traveled to the five boroughs from outside the city, booking 235,000 hotel-room nights at an average daily rate of $275, according to a study released by Mayor Michael Bloomberg and City Council Speaker Christine Quinn.

Other states see similar windfalls - or watch them pass, according to the Williams Institute, an arm of the UCLA Law School that studies gender-identity law and policy. It found:

In Washington state, same-sex marriage should generate $88 million during the next three years, including $5 million in additional tax revenue in the first year.

Texas loses out on about $60 million a year in wedding-related revenue, due to its ban on gay marriage.

Maryland same-sex couples will spend an estimated $63 million on weddings in the next three years.

"It's big," said Lee Badgett, the institute research director and a professor of economics at the University of Massachusetts, Amherst. "Many couples who want to get married, it's a special day, so they spend lots of money. They invite friends and family, and they spend lots of money."

Last week, the debate in Pennsylvania erupted, first when the ACLU filed a federal suit in Harrisburg to overturn the state law that defines marriage as between one man and one woman. On Thursday, at a noisy, crowded news conference in Philadelphia, Kane said she could not support the state ban - drawing denunciations from GOP leaders who accused her of abdicating her duty.

The ACLU suit came less than two weeks after the U.S. Supreme Court struck down a federal law that limited marriage to heterosexuals, a ruling that galvanized the same-sex-marriage movement.

"People can actually see that change can happen," said Temple University's Jason Del Gandio, who studies advocacy.

Economically, Pennsylvania could become the hole in the doughnut, surrounded by same-sex jurisdictions including Delaware, Maryland, New York, and Washington, D.C., up the coast to Connecticut, Massachusetts, Maine, New Hampshire, Vermont, and Rhode Island.

New Jersey does not allow same-sex marriage, and Pennsylvania's ban extends to disallow recognition of marriages performed in other places.

Couples here say they are leaving to spend wedding dollars elsewhere.

After 25 years together, Philadelphia health-care consultant Harvey Hurdle and architect Kevin Yoder got married in May - in Washington. Tired of waiting for Pennsylvania to act, they took a 10-person party down I-95 for a two-day celebration.

Hurdle estimates they spent $5,000 to $6,000 on hotel rooms, meals, flowers, and photos, "all money that flowed to the District of Columbia instead of Philadelphia."

"We had a small family wedding. We might have had a bigger event in Philadelphia," said Hurdle, who with Yoder is raising a 6-year-old son, Evan Hurdle-Yoder.

Others said the same.

"If I was married in Pennsylvania, I would have had a big party," said Maureen Hennessey, who in 2011 legally married another Philadelphia woman in Massachusetts.

She and her spouse, Mary Beth McIntyre, would have liked to have had a reception at the Valley Green Inn, the 1850s landmark on the Wissahickon Creek. Instead, they spent a week in Provincetown, Mass.

McIntyre died from cancer in May after 29 years with Hennessey, a plaintiff in the federal suit.

Today, more Pennsylvanians say gay people should be allowed to wed. A March poll by Franklin and Marshall College found 52 percent of voters in favor and 41 percent opposed.

Legislative bills to legalize same-sex marriage have gone nowhere. And Gov. Corbett favors a permanent ban through an amendment to the state constitution.

In Philadelphia, 9,716 marriage licenses were sold last year at $80 each. That's $777,280 in income. It's unclear how many same-sex couples might choose to marry here, as government leaders have worked on making the city gay-friendly.

The city scored 109 - higher than perfect because of bonus points - in a national evaluation of municipal laws and policies toward gays, conducted by the Human Rights Campaign, the Washington-based group that seeks equal rights for lesbian, gay, bisexual, and transgender people.

"Philadelphia is a bit of a different story than Pennsylvania. We want to make that distinction," said Meryl Levitz, president and CEO of the Greater Philadelphia Tourism Marketing Corp.

The corporation takes no position on same-sex marriage, though this year marks a decade for its campaign "Philadelphia: Get your history straight and your nightlife gay."

Martin, of Equality Pennsylvania, said people should support same-sex marriage because it's the right thing to do. And they should know the state would gain financially.

"When marriage in New York became legal, I said Pennsylvanians should go to New York and celebrate," he said, "and they should copy their receipts and send them to their legislators."

Staff writer Angela Couloumbis contributed to this article.