I don't remember WN ever operating ABQ-SAT flights but I could be wrong.
Years ago, there was a paper written by one of the faculty at The University of San Francisco about Southwest's first year. Although the article archived a long time ago, it is still accessible through the internet archive and is a must-read for those interested in the history of Southwest.
This is the part that pertains to service between San Antonio and Houston in Southwest's early years.
Surveys of Southwest's passengers departing from Houston revealed that a substantial percentage would have preferred using the William R Hobby Airport, 12 miles southeast of downtown Houston, rather than the new Houston Intercontinental Airport, 26 miles north of the city. Accordingly, in mid-November,  7 of Southwest's 14 round-trip flights between Dallas and Houston were transferred to Hobby Airport, thus reopening this old airport to scheduled commercial passenger traffic. Additional schedule revisions made simultaneously included a reduction to four round-trips each weekday of the Dallas-San Antonio flights, inauguration of three daily round-trips on the third leg of the route triangle between Houston (Hobby) and San Antonio, and elimination of the extremely unprofitable Saturday flights on all routes.
BTW, the paper also mentions that at one time Southwest offered a monthly commuter pass.
After operating a year, Southwest management decided to scrutinize the fare structure and its relationship to costs and revenues. They concluded that the airline could no longer afford a $20 fare on daytime flights. New tariffs were therefore filed with the Texas Aeronautics Commission, effective July 9, 1972; these raised Southwest's basic one-way fare from $20 to $26, established a round-trip fare of $50, and offered a $225 Commuter Club Card, providing unlimited transportation on all routes for 30 days.
I wonder how long the Commuter Club Card lasted?
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