ˌɔn dʒˈænjuːˌɛɹi twˈɛnti wˈʌn, nˈaɪntiːnhˈʌndɹɪd fˈɪfti sˈɪks, ðə ɹˈaʊt wʌz ɛkstˈɛndᵻd nˈɔːɹθwɚd tʊ ˌɛsˈeɪtʃ nˈaɪnti fˈaɪv ɪn tˈeɪlɚ, ænd ðɪ ˈiːstɚn lˈɛɡ fɹʌm ɹˈaɪsᵻz kɹˈɔsɪŋ tʊ ˌɛsˈeɪtʃ nˈaɪnti fˈaɪv wʌz ɹˌiːdˈɛzɪɡnˌeɪɾᵻd æz ˌɛfˈɛm wˈʌn θˈaʊzənd sˈɪkshˈʌndɹɪd sˈɪksti, bˌʌt wʌz nˌɑːt ɪfˈɛktɪv ʌntˈɪl ðə nˈaɪntiːnhˈʌndɹɪd fˈɪfti sˈɛvən tɹˈævəl mˈæp wʌz ɹᵻlˈiːst.
On January 21, 1956, the route was extended northward to SH 95 in Taylor, and the eastern leg from Rice's Crossing to SH 95 was redesignated as  FM 1660, but was not effective until the 1957 travel map was released.