The Rio Grande Northern Railroad was chartered in 1893 to tap into the coal field around San Carlos, TX. The line connected to the Galveston, Harrisburg and San Antonio Railroad at Chispa and ran 26 miles to San Carlos.
According to the Handbook of Texas, the RGNRR never actually operated a single train over the line, leaving that to the coal mine operation, which rented a locomotive to haul the few cars of coal produced from San Carlos to the railroad connection at Chispa.
The coal mine proved unviable however, and the railroad was abandoned in 1897, just 4 years after construction.