where does the us launch space shuttles from
Kennedy Space Center (KSC) in Florida.
Space Shuttle
Five complete Space Shuttle orbiter vehicles were built and flown on a total of 135 missions from 1981 to 2011, launched from the Kennedy Space Center (KSC) in Florida. 
wiki:19652364
Space Shuttle [SEP] Introduction
The first orbiter, "Enterprise", was built in 1976 and used in Approach and Landing Tests however it had no orbital capability. Four fully operational orbiters were initially built: "Columbia", "Challenger", "Discovery", and "Atlantis". Of these, two were lost in mission accidents: "Challenger" in 1986 and "Columbia" in 2003, with a total of fourteen astronauts killed. A fifth operational (and sixth in total) orbiter, "Endeavour", was built in 1991 to replace "Challenger". The Space Shuttle was retired from service upon the conclusion of "Atlantis"s final flight on July 21, 2011. The U.S. relied on the Russian Soyuz spacecraft to transport astronauts to the ISS from the last Shuttle flight until the first Commercial Crew Development launch on May 30, 2020.