New York ? In the past decade, India has gone from a place that relatively few Americans visited to one of the top international destinations for U.S. residents — ahead of other locales like Brazil, Switzerland and Greece.

But some travelers are now canceling plans to visit because of safety concerns following the Mumbai attacks. The Department of State has issued a travel alert for India, and it’s unclear how long it will take for tourism to the region to bounce back.

Nick Ehle, 29, a computer consultant in New York City, canceled his February trip to a friend’s wedding in Mumbai. He had planned to make a three-week trip out of it.

“It makes me overall nervous about the security there,” he said. “I was going to a do lot of the traveling by myself.”

The U.S. was the No. 1 source of foreign tourists in India in 2007, according to the Government of India’s Bureau of Immigration, followed by visitors from the United Kingdom, Bang-ladesh, Canada and France.

Travel by U.S. residents to India was up 10 percent in 2007 compared with 2006, according to the U.S. Department of Commerce Travel & Tourism Industries. Last year, India was the 11th most visited international destination by U.S. residents.

Pradip Kothari, president of Quick Travel Inc. in New Jersey, which has tours to several cities in India, said he has had some cancellations, mostly from leisure travelers. But others who were planning to see family and friends seem to be going ahead with their trips, he said.

Ronald Lewis, 29, of Denver, had been planning a trip to India in the spring or summer of next year.

“I’m specifically avoiding Mumbai now due to the attacks,” he said. “No one can predict terror anywhere in the world, but we can at least travel smart.”

Deborah Merriman and her husband Doug Stevenson, a professional speaker in Colorado Springs, Colo., were planning to leave this past weekend for India. Stevenson was scheduled to present story theater workshops in Mumbai, Bangalore and Delhi later this month. The client in Mumbai canceled last Friday.

The Mumbai attackers opened fire in several locations, including a train station, a hospital, two hotels, a Jewish center and Cafe Leopold, a restaurant popular with tourists.

Travelers don’t always react in predictable ways to terrorism. After the Madrid bombings in 2004, U.S travel to Spain increased 8 percent between 2004 and 2005.

But Abraham Pizam, dean of the Rosen College of Hospitality Management at University of Central Florida, believes the impact of the Mumbai attacks on American tourists may be long-lasting, in part because events unfolded over several days when people were home for the holidays, watching the TV footage over and over.