Here's a breakdown of the evolution:
* Peak Popularity: The 50s saw the rise of many iconic slang terms, including "cool," "groovy," "rad," "beatnik," "square," and "rock 'n' roll" itself. These terms were at their peak in the mid-to-late 50s, reflecting the cultural shift of the era.
* Carryover into the 60s: Some 50s slang terms continued to be used in the early 60s, especially by older generations. However, a new wave of slang emerged during the counterculture movement of the mid-60s, making the 50s expressions less prevalent.
* Modern Usage: Some 50s slang terms have persisted in modern language, albeit with slightly different meanings. For example, "cool" is still used, but its meaning has broadened beyond the "hip" connotation of the 50s. "Rad" and "groovy" have seen a resurgence in recent years, often used ironically or nostalgically.
Therefore, it's more accurate to say that 50s slang had a gradual decline rather than a specific end date. Its influence on language is still noticeable today, with many words and phrases finding their way into modern usage.