The San Antonio & Aransas Pass Railroad (later part of the SP) helped build the jetties at Port Aransas. Here is a barge load of equipment being shipped out to Mustang Island near Corpus Christi.
There is a little book, Rails Across the Bay; The Story of a Valiant Little Railroad. by F. A. Schmidt, published 1970, 14 pages, paperbound. Corpus Christi Public Library has three copies “for reference only” (not to be checked out.) Printed by a friend of mine, the late Fremont Johnson at his print shop in Aransas Pass.