FORT WORTH, Texas — On a busy weeknight, Travis the bouncer stood protectively at the doorway of The Library, a popular bar in downtown Fort Worth, Texas.

His job sounds simple enough: Keep underage drinkers out.

But it’s not always easy. On a busy night, about 10 fake IDs pass through his hands. In the last two years, he estimates he has seen about 1,000.

Twenty years after states began raising the legal drinking age to 21, the demand for fake IDs has swelled. Scores of underage college students depend on pieces of laminated paper as a ticket to drinking and socializing.

“Fake IDs are everywhere,” said Travis, a bouncer at a popular bar in downtown Fort Worth. He did not want his last name used because he said he fears disgruntled patrons may threaten him.

It is difficult to determine exactly how widespread the problem is, mostly because authorities rarely arrest or cite minors for having fake IDs.

But bar employees, teenagers and law enforcement officials say fakes are popular among underage drinkers.

Technology-savvy teens have turned their backs on the old-fashioned cutting and pasting and instead adopted more professional means of crafting IDs.

Armed with high-quality computers, printers and digital cameras, they can create IDs that even a trained eye can have trouble detecting. Anyone with Internet access and $50 to $150 can buy an ID.

Novelty IDs sell at flea markets for just a few dollars, but a few states have begun cracking down on sales of those cards, saying they look too similar to real licenses.

Underage drinkers often use fakes from other states, hoping bouncers will not be familiar with them, said Ron Faurot, owner of Bronco’s Sports Bar and Grill in Hurst, Texas.

That’s why many bars keep a book with examples of IDs from every state.

Some bars also use portable scanners that verify whether the ID is real. Others, including The Library where Travis works, have begun employing off-duty police officers to help check IDs.

The Texas Alcoholic Beverage Commission, which regulates bars, offers training for bartenders, servers and bouncers on identifying fake IDs, Sgt. Terry Parsons said.

“It affects their livelihood,” he said. “They’re in this business to make a living, and they know having kids in there buying alcohol will cost them.”

A bar, can face permit suspensions and hefty fines ranging from $100 to thousands of dollars for serving minors.

That does not stop many teens from using fakes.

Erin Preston, 19, a Texas Tech student from Flower Mound, Texas, said many of her friends have them.

“A couple months ago, everybody was getting them,” she said. “Then some people get busted, and it dies down for a while and then starts right back up.”

The industry worries law enforcement officials.

Amid growing concerns of national security and identity theft, fake IDs are gaining public scrutiny, said Tela Mange, spokeswoman for the Texas Department of Public Safety, which issues driver’s licenses.

“In the past it was considered more benign,” she said. “Now there’s a more sinister side to fake IDs.”

As states make it more difficult to counterfeit licenses by using features such as holograms and encoding, teenagers only work harder to copy.

In 2001, Texas began issuing vertical licenses for drivers under 21. The change was designed to give bartenders and store clerks the ability to spot an underage drinker at a glance.

Colorado has adopted a facial-recognition program that compares selected license applicants photos with a database of millions of other photos on file to identify possible duplicates.

“It’s an arms race between law enforcement and these people that are determined to make fake IDs,” Mange said.