The NASA lander that successfully touched down on Mars on July 20, 1976, was Viking 1.
Viking 1 was part of NASA’s two-spacecraft Viking program and landed in Chryse Planitia. It became the first U.S. spacecraft to land successfully on Mars and return useful data from the surface. The lander photographed its surroundings, monitored weather and analyzed Martian soil.
Its biology experiments searched for evidence of microbial activity, but their results were not accepted as definitive proof of life. Viking 1 worked on the surface for more than six years, while its companion, Viking 2, landed later in September 1976 at Utopia Planitia. InSight and Phoenix were much later NASA landers: Phoenix arrived in 2008, and InSight landed in 2018.