FBI and police investigators are seen around a vehicle in which two suspects were shot following a mass shooting in San Bernardino, California, Dec. 3, 2015. Three associates of the alleged shooters are being sought for questioning. Reuters

With the United States now averaging more than one mass shooting a day, President Barack Obama once again called on Congress to enact stricter gun control measures. But even after the massacre in San Bernardino, California, such initiatives appear stalled. That stalemate is generally attributed to the political clout garnered through more than $16 million in campaign donations by pro-gun groups including the National Rifle Association in the last decade, as well as those groups’ mobilization of their millions of members.

But another factor, often overlooked, is the gun industry’s large economic footprint in communities throughout the country -- including in key states with outsized political clout.

In all, the firearms manufacturing industry today supports more than a quarter-million American jobs, generating more than $13 billion in wages and producing more than $42 billion worth of economic impact each year, according to data compiled by the National Shooting Sports Foundation. (The organization, which is based in Newtown, Connecticut -- site of one of the largest mass shootings in American history -- describes itself as the “trade association for the firearms industry.” Its jobs figures include employment in firearms and ammunition manufacturing, distribution and sales.)

In the same way that the defense industry wields political influence through its facilities in congressional districts across the country, the gun industry has a widespread presence, as job numbers show. According to NSSF data, 22 states’ workforces employ more than 90 people linked to the gun industry for every 100,000 residents. Those top states include Colorado, North Carolina and Missouri, which are key political swing states; Wisconsin, home of U.S. House Speaker Paul Ryan; and nine states that have congressional members serving on the House and Senate judiciary committees, which oversee gun control legislation.

Equally important, those top gun-industry states include the key presidential primary states of Iowa, New Hampshire and South Carolina. New Hampshire has the single highest per-capita gun industry employment in America and, per capita, the fifth most federal firearms licenses for gun dealers, according to statistics from the Bureau of Alcohol, Tobacco and Firearms. Close behind at number 11 is Iowa -- which also ranks 7th in the nation for the total number of weapons -- such as short-barreled shotguns and machine guns -- registered under the National Firearms Act (Those statistics do include weapons at law enforcement agencies).

Taken together, the jobs figures, dealer licenses and gun supplies explain why gun-safety proposals can be politically perilous for legislators and presidential candidates: They risk not just the threat of NRA ads against them, but also the danger of antagonizing constituents and key voting blocs who have strong personal connections to the firearms industry.