Basic Training
Prior to World War II U.S. Army units handled their own training. Once hostilities began and the size of the Army increased significantly, individual unit training was no longer practical.
Replacement Training Centers (RTCs) were established in 1940 order to provide basic training for Army personnel. RTC's specialized in a particular service, such as infantry, engineers, artillery, medical corps, etc., and were tasked not only with basic combat training, but also with introductory training relating to the RTC's service area. More advanced training was handled by service schools.
Although the length of training initially fluctuated from between 8 to 13 weeks, most RTC's eventually settled on a standard training length of 17 weeks.
Paratroopers did not attend standard RTC's due to the highly specialized training they required. Service schools that handled paratrooper training also took care of the paratrooper's basic training.