Article: In the mid 1970s, various American groups (some with ties to Downtown Manhattan's punk scene, including Television and Suicide) had begun expanding on the vocabulary of punk music. Midwestern groups such as Pere Ubu and Devo drew inspiration from the region's derelict industrial environments, employing conceptual art techniques, musique concrète and unconventional verbal styles that would presage the post-punk movement by several years. A variety of subsequent groups, including New York-based Talking Heads and Boston-based Mission of Burma, combined elements of punk with art school sensibilities. In 1978, the former band began a series of collaborations with British ambient pioneer and ex-Roxy Music member Brian Eno, experimenting with Dada-influenced lyrical techniques, dance music, and African polyrhythms. San Francisco's vibrant post-punk scene was centered around such groups as Chrome, the Residents and Tuxedomoon, who incorporated multimedia experimentation, film and ideas from Antonin Artaud's Theater of Cruelty.

Now answer this question: When did the American groups begin to really get in on the post-punk movement?
mid 1970s