The Space Race between the Soviet Union and the United States occurred during which period?

The Space Race was a 20th-century competition between two Cold War rivals, the Soviet Union (USSR) and the United States (US), to achieve firsts in spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the two nations following World War II. The technological advantage required to rapidly achieve spaceflight milestones was seen as necessary for national security, and mixed with the symbolism and ideology of the time.

The competition began in earnest on August 2, 1955, when the Soviet Union responded to the US announcement four days earlier of intent to launch artificial satellites for the International Geophysical Year, by declaring they would also launch a satellite "in the near future". The Soviet Union achieved the first successful launch with the October 4, 1957, orbiting of Sputnik 1, and sent the first human to space with the orbital flight of Yuri Gagarin on April 12, 1961. The USSR also sent the first woman, Valentina Tereshkova, to space on June 16, 1963.

A period of détente followed with the April 1972 agreement on a co-operative Apollo–Soyuz Test Project (ASTP), resulting in the July 1975 rendezvous in Earth orbit of a US astronaut crew with a Soviet cosmonaut crew and co-developing the enabling docking standard APAS-75. Though cooperation had been pursued since the very beginning of the Space Age, the ASTP eased the competition to enable later cooperation.