ˌɛsˈeɪtʃ wˈʌnhˈʌndɹɪd bɪɡˈɪnz æɾ ɐn ˌɪntɚsˈɛkʃən wɪð ˌɪntɚstˈeɪt sˈɪksti nˈaɪn ˈiː slˈæʃ jˈuː.ˈɛs. ɹˈaʊt sˈɛvənti sˈɛvən slˈæʃ jˈuː.ˈɛs. ɹˈaʊt ˈeɪɾi θɹˈiː ænd fˈɑːɹm tə mˈɑːɹkɪt ɹˈoʊd wˈʌn θˈaʊzənd fˈoːɹhˈʌndɹɪd twˈɛnti wˈʌn æɾ ˌʌnɪŋkˈoːɹpɚɹˌeɪɾᵻd ɹˈʌsəltˌaʊn fˈɔːɹmɚli nˈoʊn æz bˈæɹɛdə.
SH 100 begins at an intersection with Interstate 69E/U.S. Route 77/U.S. Route 83 and Farm to Market Road 1421 at unincorporated Russelltown (formerly known as Barreda).