The Ripley Hill Road portion of Route 318 connects US 44 to Route 181. The Saville Dam Road portion, from Route 181 to Route 219, is a state scenic road, leading past the Saville Dam and Barkhamsted Reservoir.
Let's split Route 318 into three parts, from west to east:
For decades, part A (Ripley Hill Road) was locally maintained. When the Farmington River flooded in summer 1955, washing out several bridges, Ripley Hill Road was pushed into service as a temporary state road, routing traffic around the ruined bridge on US 44 in New Hartford.
In January 1957, a local state representative introduced a bill to have the state take over Ripley Hill Road permanently. On June 11, 1957, the state took over the road, as unsigned route SR 860.
Part B has been state-maintained, as part of Route 181, since 1932.
Part C was a new road, added to the state highway system in 1939 when the Saville Dam was nearly complete. The road, designated SR 418, still continues over the top of the dam.
In 1963, SR 860 and SR 418 were combined into Route 318.
After a picnic lunch at [Barkhamsted] Reservoir I headed for Pleasant Valley on Route 319 [actually 318]. Until now I'd thought of routes as the kind of thoroughfares I was trying to avoid. Not in New England. Calling a cowpath a "route" was the only case of Yankee exaggeration I'd ever encountered.