NYC I DO: Gay marriage in New York State from 25th July

Gay couples will be able to marry in New York state from July 25, and New York City hopes to woo them with an 'NYC I DO' campaign as officials prepare for an expected deluge of weddings.

An estimated 66,000 gay couples will marry in New York state within three years, adding about $284 million to the state's economy, according to a report by the Independent Democratic Conference, a separate state caucus of four Democrat Senators.

Couples from all over the United States and abroad can start applying for marriage licenses from July 5. The $35 license must be obtained before any couple can get married in New York state.

New York will become the sixth and most populous U.S. state to allow gay marriage. State senators voted 33-29 on Friday to approve marriage equality and Governor Andrew Cuomo, a Democrat who introduced the measure, immediately signed it into law.

The city's marketing and tourism group, NYC & Company, said it was developed an 'NYC I DO' campaign to make it the No. 1 destination for gay couples.

"We anticipate that the campaign, set to launch soon, will create hundreds of millions of dollars in additional economic impact to the city's $31 billion tourism industry," said NYC Company Chief Executive George Fertitta.

Some organizations have already started their own publicity, such as the Museum of the City of New York near  's Central Park, which tweeted on Monday: "Rent space at the Museum for your gay wedding! We throw a great party!"

The Human Rights Campaign in New York uses celebrities and YouTube to reach out to the public for support.