Back in the early 2010s I frequently visited Gila County Arizona. Often my travel took me up Arizona State Route 88 (usually for fun) and Arizona State Route 188. The junction of AZ 88 and AZ 188 holds what was two significant bridging structures of Roosevelt Lake; the Roosevelt Dam and Roosevelt Lake Arch Bridge.
AZ 88 is one of the oldest State Highways in Arizona dating back to 1927. While the highway was originally intended to be signed as AZ 66 the designation of AZ 88 was ultimately chosen due to US 66 being assigned over what was intended to be US 60 in Arizona. As originally signed AZ 88 stretched from US Route 80 in Apache Junction east to the first US 180 in Globe. By 1927 Roosevelt Dam was long completed since 1911 as it was the signature structure of the Salt River Project. Roosevelt Dam was used as a bridging structure from AZ 88 north to the road to Payson. This 1927 highway map of Arizona shows the location of Roosevelt Dam on the initial alignment of AZ 88.
Construction of Roosevelt Dam began along the Salt River in Gila County by 1903, as stated above the structure was completed by 1911. Roosevelt Dam and the Salt River Project were part of the 1902 Reclamation Act which paved the way for later more well known public works projects such as the Hoover Dam. Roosevelt Dam as originally completed was a completely masonry dam and was the largest of it's type at the time.
According to Arizonaroads.com the route of AZ 188 from AZ 88 at Roosevelt Dam north to Payson was designated in 1958. At the time the junction of AZ 88 and AZ 188 was at Roosevelt Dam. AZ 188 can be viewed in it's originally configuration crossing Roosevelt Dam on the 1961 State Highway Map.
In 1989 an expansion project to raise Roosevelt Dam from 280 feet to 357 began. Said project was to expand Roosevelt Dam via use of a new masonry cover over the original dam structure. The Roosevelt Dam expansion project required AZ 188 be shifted onto a new bridge over Roosevelt Lake. The new Roosevelt Lake Arch bridge was completed by 1992 and remains one of the more scenic bridges in Arizona.
According to Arizonaroads.com AZ 188 was shifted over what was AZ 88 east of Roosevelt Dam to Globe by 2000. The change was apparently instigated due to a new ADOT policy about having a highway have both terminus points at the same route.