Originally US Route 99 in the City of Merced was aligned on 16th Street. As US 99 entered Merced via 16th Street it would have crossed under the "Gateway to Yosemite Arch" at Bear Creek which was present until 1940. Much of 16th Street was largely improved by 1940 due to flooding which impacted travel on US 99 in the late 1930s. US 99 once carried multiplexes of CA 59 and CA 140 on 16th Street during the Sign State Route era. US 99 was moved off of 16th Street to a new freeway alignment through Merced which opened in June of 1964.
https://www.gribblenation.org/2021/01/former-us-route-99-on-16th-street-in.html