SAN DIEGO — For the first time, US border authorities will inspect trucks entering the United States on Mexican soil, working simultaneously with Mexican counterparts.

The new facility in Tijuana, which aims to reduce congestion and speed cargo crossings into San Diego, was built despite resistance in Mexico to letting US officials carry guns. Mexican lawmakers approved changes to the country’s firearms law to permit foreign customs and immigration officials to be armed on the job.

US Customs and Border Protection Commissioner R. Gil Kerlikowske and Mexican Treasury Secretary Luis Videgaray were scheduled to open the joint inspection facility Tuesday in Tijuana’s Mesa de Otay section, a few blocks from one of the busiest crossings on the 1,954-mile border.

Customs and Border Protection provided few details, saying the effort ‘‘represents the shared commitment between the United States and Mexico to promote economic growth and prosperity between the two countries connected by more than just a shared border.’’

It is the latest demonstration of closer border ties. Last month, a group of US and Mexican investors opened an air terminal in San Diego with a bridge that crosses a razor-wire border fence to Tijuana’s existing airport, believed to be the only cross-border airport outside the European Union.

In October, Mexican authorities began inspecting Mexico-bound cargo at the airport in Laredo, Texas. Cargo has long been inspected in both countries; the ‘‘pre-inspection’’ facilities effectively meld two stops into one.

Associated Press