A highway in San Francisco in 1986
A highway was generally any public road in a city or countryside, such as a freeway, interstate, or superhighway.
In 1930, a highway patrolman in Lee's Summit had stopped a number of cars on a highway because they had no license plates. (TOS: "The City on the Edge of Forever")
In 2256, while the Paul Stamets of the prime universe and his counterpart from the mirror universe were stuck in the mycelial network, the mirror Stamets described the network as a "mycelial highway." (DIS: "Vaulting Ambition")
In 2257, Captain Christopher Pike, in command of the USS Discovery seemed to find the concept of skipping "across the universe on a highway of mushrooms" hard to believe, as he told Saru "I kind of have to go on faith." (DIS: "New Eden")
The film called The Tardigrade in Space stated that Ephraim used the mycelial network as a "super-warp highway." (ST: "Ephraim and Dot")