Some stories in Robert Heinlein's Future History are pivotal whereas others are not. Thus, three works, "Blow-ups Happen," "The Man Who Sold The Moon" and "Delilah and the Space Rigger," are collectively pivotal between Earth-bound stories and Luna City-based stories. The stories cover the development of an escape velocity rocket fuel, the landing of a man on the Moon and the construction of a space station necessary for regular Earth-Moon flight. "The Green Hills of Earth" is pivotal between Luna City and the wider Solar System. "Logic of Empire" pivotally shows that interplanetary exploitation does not benefit everyone while an extreme political alternative gains ground on Earth. "If This Goes On -" is pivotal not only between the first interplanetary period and the Prophetic Interregnum but also between the latter and the post-revolutionary Covenant which is pivotally broken in Methuselah's Children. Pivots become more frequent as political change moves to the foreground of the series.
Gravity control, discovered in " - We Also Walk Dogs," must be lost in the Interregnum because it is absent from Methuselah's Children and "Universe" where interstellar spacecraft are spun to generate centrifugal force. Martians, Venerians, Jovians, Titans, Callistans and two other unnamed Solar races are mentioned although only the first two make brief appearances elsewhere in the History. (Since the first successful interstellar explorers meet two extra-Solar races in a single round trip, the galaxy of the Future History seems to be well populated.)
Unlike "Logic of Empire," " - We Also walk Dogs" gives no hint that "Things are bound to get a whole lot worse before they can get any better" but that is because it reflects a different segment of a complicated future society where one highly paid General Services operator has a pocket phone. The background information and optimistic tone of the story make positive contributions to the Future History.