According to Journey To Where, in 2120 the pollution of the 21st century has destroyed the natural environment. The air is too polluted to breathe. Humanity had retreated into giant metrocomplexes. In the former USA there are several metropolitan complexes: Texas City, Pacific City and Grand Metropolis, the latter covering the Eastern Seaboard from New Jersey, New York to Boston.
Below: these two images did not appear in the episode, but were shown in the Wonder Woman episode 'Time Bomb' in 1978. Around 5 large domed cities, and 3 or more smaller ones, were built. Unfortunately, in bright light they are not as effective as they could be, and the shots are further undermined by the gravel landscape, obvious painted backdrop, and, worst of all, the LED rope lights which would be more at home in a 1970s disco.
Domed cities are one of the iconic images of science fiction, memorably described in Arthur C Clarke's The City and the Stars (1956) and, particularly, Isaac Asimov's New York City in The Caves Of Steel (1953). The article from Mechanix Illustrated, November 1968, entitled "What Will Life Be Like in the Year 2008?" shows a domed city that closely resembles the Texas City domes shown in Journey To Where.
This cover painting for Perry Rhodan 20, "Thrall of the Hypno" by Angus McKie, shows a 1977 vision of domed cities, here perched like mushrooms on tall pedestals.
Contents copyright Martin Willey