Located adjacent to the port and fishing city of Guaymas, on the Gulf of California, Empalme became Stockton's third sister city in 1973. It is an important railway center for the coastal area of the state of Sonora, some 250 miles south of the US-Mexico border city of Nogales. In fact, the name Empalme in Spanish means junction and was given to the city because it is where construction of the railroad north from Guadalajara and south from Nogales met.

Unlike Stockton's other "sisters," Empalme is a small city, having a population of about 100,000 persons, but over the years, by reason of comfortable access by road, rail and air, Stockton and Empalme have shared in an extensive volume of intercity visits. These have produced a broad network of personal friendships between residents of the two cities.