This is the document which prompted the creation of the Texas Interlocking Tower web site. It was originally published by the Southwest Railroad Histroical Society in their publication called The Clearance Card. The SRHS operates the Age of Steam Museum in Dallas, Texas. Original publication date for this list Dec. 30 1993.
Published Railroad Commission of Texas data for interlockers stops at Interlocker 170 in their Annual Report for the year 1931. In subsequent years the Railroad Commission ceased publishing the annual list of interlocking towers. Research to bring the list up to the total 215 towers was done in 1986 and 1987 by William J. Neill, who was the editor of The Cross Tie, an employee magazine published for the San Antonio Division of the Southern Pacific Railroad.
