Postcard dates are typically provided on the address side, but in this case, there is none.
Nonetheless, the cars are a dead giveaway. Especially what appears to be a baby blue AMC Pacer parked near the horseback riding crew (Pacers were produced from ’75-’79)
Neat to see the C Lazy U Barn though, as it was destroyed/burnt during the East Troublesome Fire in October of 2020.