This is near Supai Summit west of Williams at milepost 382. From here the line drops more than 1,800 feet to Ash Fork. The original mainline through Johnson's Canyon was on a three percent grade. In 1911, the Santa Fe added double track between Williams and Ash Fork. The new line for eastbound trains was on a two percent grade that was three miles longer. This line split from the original mainline at Welch and rejoined at Supai.

Extra 3440 is dropping down into Ash Fork on May 20, 1978. The Santa Fe, Prescott & Phoenix opened a line from Ash Fork to Phoenix on March 14, 1895. This line replaced an earlier line from Seligman south to Prescott. Ash Fork is at milepost 401 at an elevation of 5,160 feet.