Complex sentence: Through the 1960s Colusa also had a functional freight train service, and it had two well estabished grocery stores (Herschel Harl's and the L & D store) which functioned well into the 1970s as well.
Split into simpler sentences: Through the 1960s Colusa also had a functional freight train service. It also had two well established grocery stores (Herschel Harl's and the L & D store) which functioned well into and through the 1970s as well.