Each route was extended to Sacramento in 1933 over the aforementioned county highways, taking Route 50 southeast from Rumsey to Woodland near Cache Creek and then alongside the Sacramento River to the I Street Bridge, and Route 54 west from the county line to Route 11 just outside Sacramento. The entirety of both routes, from SR 20 near Wilbur Springs through Sacramento to State Route 49 just north of Drytown (and initially overlapping SR 49 to Jackson), was included in the initial state sign route system in 1934 as Sign Route 16. Through downtown Sacramento, SR 16 followed U.S. 40 (Legislative Route 6) and U.S. 50 (Legislative Route 11), mostly on Capitol Avenue, while Legislative Route 50 continued south on 5th Street (later a one-way pair of 3rd and 5th Streets) and turned east on Broadway, carrying Sign Route 24 most of the way to Freeport Boulevard. In the 1964 renumbering, Route 16 became the new legislative designation, and Sign Route 24 through Sacramento was replaced with State Route 99 and State Route 160. As neither of these used what had been Sign Route 24 along 3rd and 5th Streets and Broadway, part of Route 16's new definition ("Route 5 near Woodland to Sacramento") was used for several years on this alignment until it became part of State Route 99 later that decade. This left the western segment of SR 16 ending at Interstate 5 near the east end of the I Street Bridge until 1984, when the Woodland-Sacramento portion, which had become redundant with the parallel Interstate 5 complete, was deleted from the legislative definition. After this, SR 16 was rerouted from the intersection with County Route E7 to continue north on a bypass of Woodland instead of east to Interstate 5.