Throughout the 1940s and 1950s the route was expanded north, but in 1968 it was truncated to its current length.
θɹuːˈaʊt ðə nˈaɪntiːnhˈʌndɹɪd fˈoːɹɾi z ænd nˈaɪntiːnhˈʌndɹɪd fˈɪfti z ðə ɹˈaʊt wʌz ɛkspˈændᵻd nˈɔːɹθ, bˌʌt ɪn nˈaɪntiːnhˈʌndɹɪd sˈɪksti ˈeɪt ɪt wʌz tɹˈʌŋkeɪɾᵻd tʊ ɪts kˈɜːɹənt lˈɛŋθ.