This is a period during the 1920s when the national attitude was positive and upbeat

Jazz Age

Explanation:

Before the great depression of 1929 Americans had money as the stock market soared (bullish market), modernism was the mainstream idea as traditional values declined, this sensation of wealth created a positive and upbeat attitude among americans

in the 1950s, country music came into its own before rock-n-roll took off in the 60s while jazz and classical music continued to innovate