The line extended to San Antonio in 1880 and finally to the US-Mexican border town of Laredo on December 1, 1881.
[3] In a bit of planned corporate maneuvering to keep the I-GN within the Mopac fold, the Gulf Coast Lines subsidiary, New Orleans, Texas and Mexico Railway, bought the I-GN on June 30, 1924; subsequently, the Gulf Coast Lines were bought by the Missouri Pacific on January 1, 1925.
Finally, on March 1, 1956, all of the GCL subsidiaries were merged into the parent Missouri Pacific Railroad Company, and the I-GN ceased its corporate existence.
[4] In the 1960s, many of the redundant out-of-the-way lines were abandoned, including Waco to Marlin and Bryan to Navasota.
The latter route was subsequently traversed via trackage rights over the Southern Pacific Railroad between the same two points.