ˌɛsˈeɪtʃ wˈʌnhˈʌndɹɪd wʌz dˈɛzɪɡnˌeɪɾᵻd ˌɔn sɛptˈɛmbɚ fˈɪftiːn, nˈaɪntiːnhˈʌndɹɪd twˈɛnti fˈoːɹ ˌɔn mˈoʊst əv ɪts kˈɜːɹənt ɹˈaʊɾɪŋ ɪn dˈiːp sˈaʊθ tˈɛksəs, bˌʌt ɪɾ ˈɛndᵻd æt ɡˈoʊmɛz stɹˈiːt ɪn pˈoːɹt ˈɪzəbˌɛl.
SH 100 was designated on September 15, 1924 on most of its current routing in Deep South Texas, but it ended at Gomez Street in Port Isabel.