NEW YORK -- The "T" in LGBT travel stands for "transgender," though it's generally the part of the acronym that travel and tourism forgot.

Overshadowed by their more numerous gay, lesbian and bisexual counterparts in LGBT circles, Americans who have switched genders are largely left to their own devices and dilemmas when planning travel based on their unique needs, interests and concerns.

Detailed information about the segment is hard to come by. Organizations tracking LGBT travel trends, such as the International Gay and Lesbian Travel Association in Fort Lauderdale and the San Francisco-based research firm Community Marketing, focus mainly, by default, on gay male and lesbian travelers.

For their part, LGBT specialist agents and tour operators report little or no traffic from identifiably "trans" clients. And most Web searches usually return results lumping transgender travelers in with gays, lesbians and bisexuals, or, less frequently, relating to sex-tourism.

What is not clear is whether this lack of data on transgender travelers is a result of their relatively low numbers or of their falling through the cracks in an industry highly focused on gays and lesbians.

"I'd say it's a little bit both ... and it's unfortunate," said International Gay and Lesbian Travel Association President John Tanzella. He noted that the "T" in his group's acronym, GLTA, stands for "travel," not "transgender."

"But it's something we have on our radar to do some research and shed some light on," Tanzella added. "Perhaps in one of our upcoming conventions we will do a general session on transgender travel."

Community Marketing, which issues an Annual LGBT Travel Survey each fall, has never received enough responses from transgender travelers to track the market, said senior projects manager David Paisley. "It's not that we've had absolutely no response, but it's been a small number," he said. "I think this year, we'll have the first significant number of such responses to make a comparison."

What little transgender-travel information can be found online usually relates to advice on airport security screening procedures, which can pose challenges for individuals in various stages of gender transitioning and whose identification documents often do not reflect their current sex status.

Vanessa Carey, a transgender traveler from Massapequa, N.Y., has slowly been transitioning from male to female for eight years.

"I bounce back and forth between genders, so my documents are all still masculine" Carey said. "I've had experiences boarding a plane or renting a car where I've had to be careful because sometimes people can be surprised or suspicious."

Both the National Center for Transgender Equality in Washington and the Oakland, Calif.-based Transgender Legal Center, while not specializing in travel issues, have posted lists of such recommendations on their websites.

The federal government is actually a leader in this area: The Transportation Security Administration (TSA) hosts a dedicated "Transgender Travelers-Special Considerations" page and the State Department's "LGBT Travel Information" page, launched in partnership with IGLTA, specifically addresses transgender issues and concerns.

When she spoke to Travel Weekly, Carey was unaware these online resources existed.

"I've just gotten used to there being no resources out there, so I haven't really looked," she said. "We transgendered people do share [travel] stories; it's actually a pretty common topic of conversation."

Concerns range from clearing airport security and then renting a car or hotel room to simply choosing the right public restroom in a given destination.

"In a lot of [U.S.] states ... you break the law just by using the 'wrong' bathroom," she noted. "Even here in New York, the city legally protects transgendered people, but the state doesn't. I could legally be denied service in a restaurant."

As to which travel products out there are specifically designed for transgender consumers, Paisley pointed to a half-dozen group events and conferences held annually across the country. These include Fantasia Fair in Provincetown, Mass., which this year runs from Oct. 20 to 27; the Southern Comfort Conference in Atlanta (Sept. 4 to 8); and Diva Las Vegas, next set for March 30 to April 4, 2014.

"These are groups that destinations do actively go after; the transgender group travel market is actually discussed in the broader travel market," Paisley said. "But the individual transgender traveler market is not as well documented, at least to my knowledge."

When queried about individual transgender clients, gay and lesbian travel agents had little to report. Sandra Pollack, co-owner of Journey Weavers Educational Travel in Ithaca, N.Y., said she wasn't sure why she has no transgender clients.

"In Ithaca, a pretty progressive place, we have a transgender community, but I haven't had any requests," she said. "I just don't know what that exactly means, whether it's related to comfort levels or what. I hope it changes."

For her part, Carey books most of her own travel but would consider using a trans-friendly agent -- though with some skepticism.

"If someone puts out a shingle saying they're receptive to the transgender community, I appreciate the sentiment on one hand," she said. "But as a bit of a cynic, I also suspect they're just engaging in some savvy marketing."

Peter Greene, co-founder of Now Voyager World Wide Travel Services in San Francisco, said he doesn't think transgender travelers are "necessarily a niche market, where they want to travel together."

"Their lives might be about integrating and not separating, which is a good thing that I completely understand."

Greene just returned from a gay cruise in Alaska, and the sole transgender person aboard was an entertainer, he said.

Carey agreed that transgender travelers often prefer to blend in, in mainstream destinations.

"If I travel, I'm going to go to any part of the country where I'd like to see the sights, enjoy myself and be inconspicuous." But she also noted that a destination's reputation for safety is a prime concern.

Moreover, she said she don't always feel comfortable or welcome in all-gay venues.

"I like doing some of the gay-themed stuff, but even there you can feel a little bit like an outsider," she said. "On gay singles cruises, for example, I'm not going to meet anybody. It wouldn't be appropriate for me."

For all the shared experiences and common cause among transgendered people, gays, bisexuals and lesbians, that feeling can be mutual.

"We can put all the letters [LGBT] together and say we're a community, but there are gay men who only want to travel with other gay men," said Gregg Kaminsky, owner of R Family Vacations. "Not that they're against any other segment of the LGBT community, but we're not all the same."

Carey lays some of the blame for a lack of trans-travel information and product at her community's own doorstep, saying "T" rights and advocacy efforts are 15 years behind the "LGB" curve.

"I can respect the desire to simply blend in and get on with life," she said. "But because transgender people aren't as vocal or activist, there's still silence and more of a taboo around us. I can get frustrated at times."