According to the U.S. Census Bureau Statistical Abstracts from 1931 to 1939 the U.S. Nonfarm Unemployment Rate averaged 29.2% with a peak of 37.6% in 1933. By 1939 it was still 25.2%. This was a result of the "stimulus" economic measures enacted by Presidents Hoover and Roosevelt, which included much higher taxes, much more regulation, huge increases in government spending, and a tremendous expansion of government (sound familiar?). The consequent malaise lasted right through WWII until the end of the 1945 recession, with hyper-inflation in 1946, and a falling GDP until 1947. (Liberals like Paul Krugman today insist that the war stimulated the economy – except that the malaise in non-war sectors of the economy persisted and the war ended with the whole economy in a recession, as do most wars. Living standards under war rationing and price controls had still not returned to the level of the late 1920s.)
As a comparison, following the 1920 Depression (which was deflationary and worse than the Great Depression), President Harding responded with austerity measures of drastically reducing taxes, regulations, government spending and the size of government. The depression was over in less than two years. From 1923 to 1929 unemployment averaged 5.5%.
Using a similar unemployment measurement standard today results in an average rate since the 2008 financial crisis above 14%. It would be much higher, except that unlike then, today there are many government entitlement programs.
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