Final answer:
Country POP started to achieve success in mainstream charts in the 1970s, blending traditional country with pop elements.
Step-by-step explanation:
Country POP became a significant success in mainstream charts starting in the 1970s. This genre blends traditional country music with pop music elements, creating a sound that appealed to a wider audience. While country music had been popular on its own, the crossover appeal of country POP began to rise in the 70s, leading to the genre's prominent presence in mainstream music charts. Acts like John Denver, Olivia Newton-John, and Dolly Parton helped to pioneer and popularize this style, contributing to its lasting success.