The main facility sprawls across multiple acres in the Mountain Empire region of southeastern San Diego County. Here, volunteers maintain and operate vintage diesel-electric locomotives that pull excursion trains through terrain that challenged railroad builders a century ago. The museum's collection spans the entire mechanical evolution of American railroading - from early steam power to mid-century diesel technology. Walk the grounds and you pass locomotives that once hauled freight across deserts, passenger cars that carried travelers before interstate highways existed, cabooses where conductors watched the rails recede into distance. Each piece arrived through donation, rescue, or careful acquisition, saved from scrapyards by enthusiasts who saw history worth preserving.

The museum's reach extends beyond Campo. In downtown La Mesa, adjacent to the Orange Line trolley station, stands the original La Mesa depot - the oldest building in town and the sole surviving station of the San Diego and Cuyamaca Railway. The museum's restoration of this Victorian-era structure earned recognition from Save Our Heritage Organization, San Diego's historic preservation society. A display train sits beside the depot: the Mojave Northern Railroad's saddletank steam locomotive number 3, a Pacific Fruit Express refrigerator car that once kept California produce cold on cross-country journeys, and a Southern Pacific caboose anchoring the consist.

The photogenic locomotives and frontier-era depot haven't escaped Hollywood's notice. In 1994, the children's video "There Goes a Train" featured the Campo facility, with the museum closing for a full week of shooting. The museum's ALCO MRS-1 locomotive, originally built for the United States Air Force, pulled a three-car excursion train east through the desert landscape. Five years later, Irish pop group B*Witched arrived to film the music video for their hit single "Jesse Hold On," featuring Southern Pacific locomotive 2353 as their steel co-star. The museum's authenticity - actual working trains on actual historic tracks - offers something soundstages can't replicate.

What makes the Pacific Southwest Railway Museum remarkable isn't just what it preserves but how it operates. Every excursion train runs on volunteer power - engineers, conductors, and docents who show up on weekends to keep history moving. The San Diego and Arizona Eastern line they travel was called impossible for good reason: the route through Carrizo Gorge required tunnels, trestles, and engineering audacity that nearly bankrupted its builders. Much of that original line remains dormant, but at Campo, the locomotives still warm up on Saturday mornings, the air brakes still hiss, and passengers still climb aboard to feel the rhythm of flanged wheels on steel rails - the heartbeat of an industry that built the West.