tˈuː fˈɜːðɚɹ ɛkstˈɛnʃənz, tʊ ˌɛfˈɛm ˈeɪthˈʌndɹɪd twˈɛlv ˌɔn sɛptˈɛmbɚ twˈɛnti, nˈaɪntiːnhˈʌndɹɪd sˈɪksti wˈʌn ænd jˌuːˈɛs wˈʌnhˈʌndɹɪd ˈeɪɾi θɹˈiː ˌɔn dʒˈuːn twˈɛlv, nˈaɪntiːnhˈʌndɹɪd sˈɪksti ˈeɪt, bɹˈɔːt ðə ɹˈaʊts sˈʌðɚn tˈɜːmɪnəs tʊ ɪts kˈɜːɹənt loʊkˈeɪʃən.
Two further extensions, to  FM 812 on September 20, 1961 and US 183 on June 12, 1968, brought the route's southern terminus to its current location.