Short answers, pulled from the story.
Air Force Colonel Edward N. Hall led the development of solid fuel propulsion for the LGM-30 Minuteman missile in 1956. He directed research at Boeing and Thiokol into ammonium perchlorate composite propellant to create a ready-to-launch system.
The LGM-30G Minuteman III program started in 1966 with its first test launch occurring on the 16th of August 1968. It entered service in 1970 carrying up to three W62 Mk-12 warheads each yielding only 170 kilotons.
Forty-five hundred LGM-30G missiles are emplaced across three active wings as of the latest inventory count. Francis E. Warren Air Force Base in Wyoming hosts the 90th Missile Wing, Minot Air Force Base in North Dakota maintains the 91st Missile Wing, and Malmstrom Air Force Base in Montana supports the 341st Missile Wing.
SAC realized that Soviet planners could disable the entire force by targeting just 100 Minuteman Launch Control Centers using far fewer resources than attacking every silo individually. The EC-135A ALCS aircraft demonstrated its capability on the 17th of April 1967 to launch missiles even after ground command centers were destroyed.
Northrop Grumman won the competition to build the future ICBM since their bid remained the only one left after Boeing dropped out earlier that year. It was announced on the 14th of December 2019 that Northrop Grumman would proceed with aggressive sole-source negotiations to replace aging Minuteman III systems currently operated by three operational wings.