ˌɛsˈeɪtʃ sˈɛvənti θɹˈiː ˈeɪ wʌz dˈɛzɪɡnˌeɪɾᵻd ˌɔn dʒuːlˈaɪ ˈeɪtiːn, nˈaɪntiːnhˈʌndɹɪd twˈɛnti fˈoːɹ, fɹʌm ˌɛsˈeɪtʃ sˈɛvənti θɹˈiː ɪn fˈeɪətvˌɪl tə hˈɛmpstɛd æz ɐ ɹˌɛstɚɹˈeɪʃən ʌv kˈænsəld ˌɛsˈeɪtʃ θɹˈiː sˈiː. ˌɔn mˈɑːɹtʃ nˈaɪntiːn, nˈaɪntiːnhˈʌndɹɪd θˈɜːɾi, ðɪs ɹˈaʊt wʌz ɹᵻnˈʌmbɚd ˌɛsˈeɪtʃ wˈʌnhˈʌndɹɪd fˈɪfti nˈaɪn.
SH 73A was designated on July 18, 1924, from SH 73 in Fayetteville to Hempstead as a restoration of canceled SH 3C. On March 19, 1930, this route was renumbered SH 159.