But states in the Northeast, like New York, have some of the lowest rates of gun ownership in the country, Professor Egan said, a fact that influences views about firearms. In addition, some of the worst mass shootings in recent years, like those in Aurora, Colo., and Newtown, have occurred in suburban areas.

“In terms of attitudes about guns, we have seen a big urban-suburban and rural divide open up across the country in the past 40 years,” he said. “This is one more indication that guns have become a flash point in the political and ideological polarization of our nation.”

Town officials say they learned about plans for the gun shop in mid-September. Because the retail space had been occupied by a learning center, Mr. Zacchio needed a permit changing the use from “retail services” to “retail.” He was granted it in October.

The 450-square-foot space is tucked away in a mini-mall within 1,000 feet of a public elementary school. “I would expect phone calls and an outcry if was trying to open a Romantic Depot or strip club,” he said. “It’s not like I’m selling guns from a truck.”

As the town attorney, Frank P. Allegretti, explained at the town-hall-style meeting, officials had little control over the gun store’s presence. Like other municipal ordinances in Westchester County, Harrison’s laws do not explicitly prohibit firearm retailers. If it were to ban them, he said, the town would open itself to legal challenges.

“This gentleman has the right, as anyone else does, to open a store there,” he said. “There are constitutional rights, Second Amendment rights.”