While marriage is legal only between one man and one woman in Georgia, same-sex unions are lawful in a majority of America. Here are the states where gay marriage is illegal.

Alabama*

Arkansas

Georgia

Kentucky

Louisiana

Michigan

Missouri

Mississippi

Nebraska

North Dakota

Ohio

South Dakota

Tennessee

Texas

*Alabama Supreme Court halted gay marriage March 3, despite a federal district judge’s ruling in late January that allowed same-sex unions after declaring the state’s ban on gay marriage unconstitutional.

The Williams Institute at UCLA, a think tank that studies the gay population, estimates gay marriage could have an economic boost nationwide of $2.6 billion. The numbers include all spending on planning and wedding events by the couple, their relatives and guests.

Here are the estimates for a few of the largest states.

1. California: $392.3 million, estimated spending over first three years

2. New York: $228.6 million

3. Florida: $182.2 million

4. Texas: $181.6 million

5. Massachusetts: $111.2 million

6. Illinois: $103.2 million

7. Pennsylvania: $92.1 million

8. Washington: $88.5 million

9. New Jersey: $82.5 million

10. Georgia: $78.8 million

They bought wedding rings at Cartier at Lenox Square mall. An Atlanta travel agent booked their two-week honeymoon to Paris. At least 120 guests celebrated their nuptials in a ceremony at Barnsley Gardens Resort in Adairsville.

When the time came for Atlanta real estate attorneys Joseph Henson and Robert Cook officially to exchange rings, they went to Massachusetts, where marriage between two men is legal.

Even so, their wedding-related spending at home provided a preview of what some Georgia businesses think will be a boost if same-sex marriages become legal nationwide.

“We spent thousands of dollars and it was good for the local economy,” Cook said of the couple’s $30,000 Barnsley Gardens ceremony last September, two months after the marriage in Provincetown, Mass.

“We only looked elsewhere (to marry) because we wanted it to be legal,” Cook said.

Some metro area caterers, photographers, hotels and event centers are already preparing for new business if the U.S. Supreme Court rules this summer that gays have a constitutional right nationwide to marry.

They are changing sales brochure language from “bride and groom” to “couples” to cover all the bases. They are advertising their services in gay and lesbian magazines and websites and using word of mouth at gay-oriented community events and meetings that they want metro Atlanta to be the Southeast destination for LGBT (lesbian, gay, bi-sexual and transgender) weddings.

“From our point of view this is already our customer and our partner and they already have this new need,” said Walter Woods, a spokesman for downtown’s Hyatt Regency, which annually hosts the dinner for the gay organization Human Rights Campaign and whose workers have represented the hotel in Atlanta Gay Pride parades.

Extending marriage to same-sex couples in Georgia could have an estimated $78.8 million economic impact over three years, according to a 2014 study by the Williams Institute at UCLA, a think tank that studies the gay population. The impact nationally would be about $2.6 billion, the study determined.

The effect could be magnified in metro Atlanta, for years the central hub for gays in the Southeast.

Some objections

Serving gay marriage customers has been controversial. In several states where gay marriage is legal, bakeries and florists that have refused to serve gay weddings based on religious objections have been sued or closed their businesses to avoid playing a role in proceedings of which they object.

As a result, several states, including Georgia, have passed or are debating so-called “religious liberty” legislation that critics say would seek to protect businesses that refuse to work with customers based on religious objections. Georgia’s legislation, S.B. 129, passed the Senate on March 5 and is now being considered by the House.

Opponents argue that “religious liberty” bills are designed to discriminate against gays and lesbians and their passage into law have been mixed. The sponsor of Georgia’s bill, state Sen. Josh McKoon, R-Columbus, calls it “a simple, modest, common-sense protection for people of every faith.”

In any case, many businesses are ready to capitalize on a niche even if some pass.

“We decided to step up our marketing efforts last summer after getting a call from two women asking if we did rentals for ceremonies,” said Danny Flanders, a spokesman for Atlanta Botanical Garden. “When we told them we did they became very emotional. They said they had been turned away by so many places that they were at their rope’s end for finding a location.”

The Four Seasons Atlanta recently updated its website to prominently display the nuptials of two men on its wedding page and has created a wedding cake whose traditional white frosting hides the colors of the gay rainbow flag within, said Claudia Aguas, the Midtown hotel’s director of catering.

Long-time photographers Cindy Brown and Sharon McMahon, who shoot both gay and straight weddings, set up a separate company — Same Sex Wedding Photographers — to specifically improve online search engine optimization in anticipation of what they hope will be an explosion in business.

The Atlanta Evergreen Marriott Conference Resort in Stone Mountain is expanding its definition of “bride” and “groom” packages while caterer Kate Holway of Three Sisters Catering is getting the word out that Atlanta has great gay-friendly wedding venues such as the Fox Theater and Callanwolde Fine Arts Center.

Language workshops

And Erica Prewett of wedding planning firm A Big To Do Event has been conducting workshops with vendors on language to use with gay customers, rewriting contracts that list “bride and groom” to say “client 1” and “client 2” and the importance of hiring servers sensitive to gay events.

“It’s our job to be advocates for our clients so they don’t have to be,” she said.

Despite their enthusiasm, it may take time for the gay marriage market to grow if the Supreme Court ruling opens the door.

As states or courts have legalized same-sex marriage — gay unions are lawful in 36 states - most couples have rushed to courthouses and wed quickly. The fear that courts could stop weddings — such as the recent move by Alabama’s Supreme Court to suspend gay unions in that state — convinced most to forgo long planning in favor of quick ceremonies.

Advocates think that will change if a ruling clarifies the legal landscape.

“You’re going to have a different feeling that you can relax and plan a wedding because this is the law of the land,” said Stuart Gaffney, a spokesman for Marriage Equality USA.

Tony Conway of Legendary Events agreed. “It will definitely give so many the time to plan, to send out invitations, to have family and friends to come out.”