Crossing of the San Antonio & Aransas Pass Railway with the with the St. Louis, Brownsville and Mexico Railway
In 1904, the SA&AP railroad sought to extend its rails to the Rio Grande Valley of Texas. The impetus to serve the Valley may have come from previous owner Southern Pacific (SP) wishing to compete with a new rail line to the Valley being built by the St. Louis, Brownsville & Mexico (SLB&M) Railway. The SA&AP was divested from SP ownership by court order in 1903, but the SA&AP proceeded with SP's plans to build to the Valley from the nearest service point, the town of Alice. In 1904, construction began and the first 36 miles was completed from Alice south to Falfurrias. The Valley was less than 80 miles away, but construction stopped and was not restarted until the SA&AP was re-acquired by SP in 1925. By that time, the Valley had been served for many years by the SLB&M with routes consisting of their main line from the north into Brownsville via Harlingen, and a lengthy branch line from Harlingen to Rio Grande City. Under SP ownership, SA&AP construction reached the Valley in 1927 and expanded in multiple directions that same year including a 63-mile line from Edinburg to Brownsville. This Brownsville line crossed the SLB&M at Harlingen at Tower 138.
By the time of SA&AP's arrival in the Valley, another railroad, the San Benito & Rio Grande Valley (SB&RGV) Railway, already operated 65 miles of track in the area. The SB&RGV had been acquired by the Gulf Coast Lines in 1916 but had continued to operate under its own name primarily functioning as additional branch lines for the SLB&M. In 1928, the SB&RGV built a 19-mile line east from San Benito to Abney, ultimately reaching Port Isabel on the Gulf coast. This line crossed the new SA&AP line to Brownsville at a location a couple of miles north of the town of Los Fresnos that became known as the community of Laureles. It is not known whether the name "Laureles" was in use at that time of construction, but for whatever reasons, the interlocker site became known as "Rosita" in Railroad Commission of Texas (RCT) documentation. Fortunately, Laureles is known to be the interlocker site, confirmed by a notation in the Tower 151 file in the RCT documentation repository at DeGolyer Library on the campus of Southern Methodist University.
Tower 151 was commissioned as an 11-function mechanical cabin interlocker on 17 April 1929, but the SLB&M was listed as SA&AP's crossing partner, not the SB&RGV. The line from San Benito was still operated under the SB&RGV name, but both the SLB&M and the SB&RGV were under common Gulf Coast Lines ownership at the time, and the SLB&M was clearly the dominant operating element in the Valley. The Gulf Coast Lines legal ownership entity, the New Orleans, Texas & Mexico Railroad, did not operate in the Valley. Since Tower 151 was a crossing of a main line (SA&AP) with a branch line (SB&RGV/SLB&M), it is unsurprising that a cabin interlocker was selected. In this arrangement, the cabin would have been operated exclusively by SB&RGV/SLB&M personnel to line the signals when they needed to cross, and line them back for unimpeded operation by the SA&AP when the crossing was completed.
The Gulf Coast Lines were eventually consolidated with other railroads under Missouri Pacific (MP) ownership, and in 1982, Union Pacific (UP) acquired MP. By this time, MP had long been the dominant carrier in the Valley. SP had abandoned their main line south through Edinburg and had begun sharing MP's ex-SLB&M main line into the Valley that ran south from the Houston area at Tower 65. In the mid-90's, UP acquired SP and with it, SP's remaining tracks in the Valley including the former SA&AP line into Brownsville which continues in use today. The line from San Benito to Port Isabel had been abandoned much earlier, in 1969, and with it, the need for Tower 151.
Map of Tower 151 Location Maps
Above: a TopoUSA map annotated to show the crossing
Below: a 1955 USGS Topographic map showing the precise location of the Tower 151 crossing in the center of the image
Above: It is apparent from the USGS map that the SB&RGV (Missouri Pacific) line was located a short distance south
of Bingley Road (FM2893) and a substantially larger distance north of Kretz Road, both of which still exist. The right-
of-way appears to have passed parallel to and slightly south of what is now Delta Drive.
Below: Facing east with the UP tracks crossing the image in the distance, this appears to be a view along the former
SB&RGV right-of-way. The Tower 151 interlocker cabin would likely have been visible from this vantage point (and perhaps resembled the shed
visible in the distance to the right.)