Why was the apollo 11 space mission a giant leap for America?
Apollo 11 was the first manned mission to land on the moon.
From the Wikkipedia link
At 2:56 UTC on July 21, six and a half hours after landing, (Niel)Armstrong made his descent to the Moon surface and spoke his famous line "That's one small step for (a) man, one giant leap for mankind". (Buzz)Aldrin joined him, saying, "Beautiful. Beautiful. Magnificent desolation."
Please note that, while it was the United States that sponsored most of it, the quote is "...a giant leap for mankind". The Moon Missions involved people from all the way around the Earth
from ^ a b c d e f Richard W. Orloff. Apollo by the Numbers: A Statistical Reference (SP-4029). NASA.