On July 10, 1962, U.S. Patent No. 3,043,625 issued to Nils Bohlin an engineer for Volvo on the three-point safety belt:

Lap belts and even chest belts were known in the prior art. Bohlin’s invention was securing all the three points of anchoring to the vehicle itself and not to the seat. This safety belt was incorporated in Volvo cars since 1959, the year the application was filed. and Volvo made the invention freely available to other automobile manufacturers.

The idea for an air bag actually predates the three-point safety belt, the first vehicle air bag being patented by Hetrick (U.S. Patent No. 2,649,311) in 1953:

However, the first airbags were not ready for prime time. and it was not until the 1970 that airbags started to be incorporated into cars, and not until the late 1980’s and early 1990’s when they were widely available. It was not until September 1, 1998, that the Intermodal Surface Transportation Efficiency Act of 1991 finally made air bags mandatory on cars and light trucks.