<human>:  When did the NSA and other National Security agencies start collecting data on Americans?
<bot>: They started collecting data on Americans in the 1970s. The NSA started as the National Security Agency, which was established in 1952. It was initially tasked with intercepting communications of foreign powers, but it evolved into a large organization that collects signals intelligence, or SIGINT, which is electronic communication intercepted without the knowledge of the sender or receiver. The NSA is not allowed to spy on Americans, but it does collect some information on Americans.