The frequency of mass shootings and other forms of gun violence have made Americans increasingly paranoid about who should own a gun and why. While gun laws do help to limit legal gun ownership, there are weapons working their way through the black market as well — but how?

According to the NY Times, residents from regions with stricter gun laws often purchase the gun they want from states with more relaxed laws. California, for instance, has some of the toughest gun laws in the country. Despite its best efforts, guns come in primarily from Texas, Kansas and its neighboring states. One of the most common ways to smuggle guns into California is via FedEx.

Chicago residents who want guns have an easier chance of getting one. They simply drive across state lines into Indiana, buy the gun they want, and then drive back. Florida has a more international gun trafficking ring, which sometimes sends guns all the way to Puerto Rico smuggled in an old car shipped to the country.

Some states are also more heavily armed than others due not only to gun laws but local cultures. Business Insider estimates that Arkansas is third in line when it comes to this. For every 100,000 residents of the state, there are 41.6 guns. Less than half of these are pistols.

As acts of violence continue to take place, Americans will only become more and more paranoid. While it is unlikely to result in limits at the federal level, many states may continue to tighten their laws. They may also keep a keen eye out for smuggling and the use or ownership of unauthorized weapons.