With fireworks bans in place in many parts of the southwest, there is concern some border residents will buy their supply in Mexico.
But authorities have issued a warning.
At busy border crossings officers are on the look out for contraband. This time of year that includes fireworks.
"It's important they don't purchase them for their own safety and don't attempt to smuggle them through the port of entry," says Ruben Jauregui, with U.S. Customs and Border Protection.
In addition to concerns about sparking a wildfire in the bone dry southwest, authorities warn Mexican fireworks can pose a personal safety hazard.
"You just never know how much of the powder was used on there, how powerful it is, the fuse: how short, how long? and these are the things that are not regulated," says Jauregui.
Fireworks are legal and sold openly in Mexico for major holidays like New Year's. This time of year they are banned in the border city of Juarez, but they are still available - secretly.
One vendor in Juarez says she has a variety of fireworks for sale in time for the Fourth of July. She says she has customers who are going to buy their supply in Mexico, and then smuggle them across the border to the U.S.
Officers at the border hope to snuff out any plan to bring illegal fireworks into the country. They warn those that try it will face fines as high as $5,000.