SH 46 was formerly part of
State Highway 58. As designated in 1912–1914, Primary Road No. 58 connected
Central City and
Golden, leaving Central City on Gregory Street (former
SH 279) and following present
SH 119 alongside
North Clear Creek. It turned northeast on Smith Hill Road and then, as originally defined, along present Golden Gate Canyon Road (including about of modern SH 46) past
Guy Hill. Some early maps, however, show the state highway following Crawford Gulch Road significantly north of Guy Hill. By May 1923, the west end had been shifted north to SH 119 north of Central City and Black Hawk, and at about the same time the Golden Gate Canyon Road alignment was permanently adopted. (SH 58 was also extended east from Golden to
Denver along what had been Primary Road No. 1, and the number remains to this day on a parallel freeway replacement.) As part of a 1953 reorganization that eliminated a large number of state highways, SH 58 was cut back to its modern Denver-to-Golden extent. Former SH 58 west of Golden Gate Canyon State Park was reacquired in 1972-1973 as a new State Highway 46 and paved in 1974. In 1985-1986 SH 46 was extended east to the county line along already-paved county road, and at the same time Jefferson County completed the paving of its section of Golden Gate Canyon Road. ==Major intersections==