ˌɔn dʒˈuːn twˈɛnti fˈoːɹ, tˈuː θˈaʊzənd tˈɛn, ˌɑːɹɹˈɛm twˈɛlv wʌz ʃˈɪftᵻd tʊ ɐn ɐlˈaɪnmənt sˈaʊθ ʌv sˌæn mˈɑːɹkoʊz, ænd ðɪ ˌɛsˈeɪtʃ ˈeɪɾi dˌɛzɪɡnˈeɪʃən wʌz ɛkstˈɛndᵻd θɹuː ðə sˈɪɾi tʊ ɐ tˈɜːmɪnəs wɪð ˌɑːɹɹˈɛm twˈɛlv wˈɛst ʌvðə sˈɪɾi.
On June 24, 2010, RM 12 was shifted to an alignment south of San Marcos, and the SH 80 designation was extended through the city to a terminus with RM 12 west of the city.