There were political implications, as well, according to Anne Platoff, a historian who wrote about the Apollo 11 flag in a paper, "Where No Flag Has Flown Before."
She said the United Nations had passed a treaty stating "outer space, including the moon and other celestial bodies, is not subject to national appropriation."
The United States would not and could not claim the moon.
Instead, raising the flag would be a symbol of the single-minded pursuit that began with President John F. Kennedy's pledge to Congress on May 26, 1961.
"I believe this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth," Kennedy said. "No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space, and none will be so difficult or expensive to accomplish."
Now there are six U.S. flags on the lunar surface, left by the crews of each Apollo mission. Each flag was deliberately designed with the same flaw to prevent the horizontal telescoping rod from fully extending.
When astronauts from the United States return to the moon around 2020, the crew most likely will represent several nations, so flags from other nations probably will join the six U.S. flags.