Tighter security measures designed to stop suspected terrorists, sexual predators and other types of criminals at the nation's borders will begin next month, federal officials announced Thursday.

The security program, known as US-VISIT, will require fingerprint scans and photographs of travelers who enter the United States with a visa and then apply to obtain a tourist permit. The program will begin Nov. 15 here, the nation's second-busiest land port of entry, and in Douglas, Ariz., and Port Huron, Mich. It will be expanded to the 50 busiest land ports of entry by the end of the year and to all 165 by Dec. 31, 2005.

The Department of Homeland Security implemented the program Jan. 5 at 115 airports and 14 seaports.

Among the goals of US-VISIT, the U.S. Visitor and Immigrant Status Indicator Technology program, are "to enhance the security of our citizens and visitors; facilitate legitimate travel and trade; [and] ensure the integrity of our immigration system," program director Jim Williams said.

It requires visitors to submit to inkless finger scans and digital photographs to allow Customs and Border Protection officers to determine whether the person applying for entry is the same one who was issued a visa by the State Department.

In addition, the biometric and biographic data will be checked against watch lists of suspected foreign terrorists and databases of sexual predators, criminals wanted by the FBI and people deported previously from the United States.

Williams said that since the US-VISIT program began, 280 people have been detained, out of about10 million scanned.

Implementing the program along the Mexican border, where U.S. communities such as Laredo depend on the flow of commerce and foreign visitors to sustain their economy, presents special challenges, federal officials acknowledged.

Texas, which shares a 1,200-mile border with Mexico, has 22 of the nation's 50 busiest land ports of entry. Laredo has annual crossings by 4.6 million pedestrians, 1.4 million trucks, 6.8 million private vehicles and more than 40,000 buses, according to Customs and Border Protection statistics.

"We have to implement it . . . so it will not have an impact on the cross-border traffic that is so vital," said Jayson P. Ahern, assistant commissioner of Customs and Border Protection. "Mexico has and will continue to be a key partner to these communities."

Most Mexican citizens who use border-crossing cards to travel into the United States will not be subject, at least for now, to the US-VISIT program, officials said. About 6.8 million Mexicans use such a card to travel within 25 miles of the border in Texas, California and New Mexico, and within 75 miles of the border in Arizona. The card is embedded with finger scans and a photograph and is inspected at land crossings. It permits the holder to stay for as many as 30 days.

If the card holder wants to travel farther or stay longer, he or she must undergo US-VISIT processing.

Because most Canadians generally are not required to have visas to enter the United States, they will not be subject to the US-VISIT process, officials said.

"We are cautiously optimistic [US-VISIT] won't impede trade or traffic or people that are so used to crossing our borders: our shoppers and visitors and families, our workers who choose to live on the Mexico side," said Laredo Mayor Elizabeth G. Flores. "Our relationship with our sister city [Nuevo Laredo] and with the rest of this country of Mexico is the lifeblood of Laredo."

Officer Fred Cobbs, Jim Williams of US-VISIT, center, and Jayson P. Ahern of Customs and Border Protection address plans that will affect additional U.S. land ports of entry Nov. 15.