Warren, you are compared apples with oranges. In your 1980-2000 comparison you are including the tax-cut stimulus in 1981. In your 1945-1973 comparison you leave out the demand stimulus over 1941-45 and begin your comparison with the start of austerity after the war. Here are the figures. The government ran enormous deficits to fund the war. During this time growth was spectacular. When the war ended so did the war spending and the deficit shrank rapidly from 21% in 1945 to 7% in 1946 and to a 1.6% surplus in 1947. As a result negative GDP growth was seen in 1945, 46 and 47. You chose to include all the negative impact of unwinding the war spending while leaving out all the growth that had happened in the previous years. Most of the post war decline was the war economy falling back to peacetime baseline (but even with the 7% decline in 1946, GDPpc in that years was 44% higher than it had been in 1940). In other words the majority of the WW II economic expansion was retained.
1946 was a banner year for business; consumers were flush with saving that they could not spend during the war years because of rationing. This can be seen by the S&P500 index values I provide. So 1946 is remembered as a prosperous year even though its economic stats are terrible. This of course is because the country had to returned to a peacetime economy. Factories were running to make consumer goods to meet market demand and not running flat out to make as much war materiel as humanly possible. So GDP was lower in 1946 but actual consumption higher.
Year GDPpc Fiscal Bal S&P500
1941 16.6% -3.8% 9.8
1942 17.6% -12.4% 8.7
1943 15.4% -26.9% 11.5
1944 6.7% -21.2% 12.5
1945 -2.0% -20.8% 15.2
1946 -12.5% -7.0% 17.1
1947 -3.0% 1.6% 15.2
1948 2.4% 4.3% 15.5
1949 -2.3% 0.2% 15.2
1950 6.9% -1.0% 18.4
If you really want to do an apples to apples comparison and want to compare demand versus supply-side stimulus you would compare 1981-2000 (business cycle peak to peak) to 1937-1973 (again peak to peak) In this comparison the effects of the stimulus (WW II and 1981 tax cut), the post-stimulus recession, and the "afterglow" for both periods are considered.
Alternately if you don't want WW II massively affecting your results you would start your comparison well clear of it. This is why I initially chose 1950 and 1980 as my terminal points (Notice the round years ending in zero). Since you put attention on the late 1960's I put in an arbitrary breakpoint in 1965. I chose those specifically to avoid a charge of cherry picking, which you made anyways. A commonly used period is 1947-73 because 1947 is when NIPA data begin. Data before 1947 is reconstructed/estimated by historians.
1946 was a banner year for business; consumers were flush with saving that they could not spend during the war years because of rationing. This can be seen by the S&P500 index values I provide. So 1946 is remembered as a prosperous year even though its economic stats are terrible. This of course is because the country had to returned to a peacetime economy. Factories were running to make consumer goods to meet market demand and not running flat out to make as much war materiel as humanly possible. So GDP was lower in 1946 but actual consumption higher.
Year GDPpc Fiscal Bal S&P500
1941 16.6% -3.8% 9.8
1942 17.6% -12.4% 8.7
1943 15.4% -26.9% 11.5
1944 6.7% -21.2% 12.5
1945 -2.0% -20.8% 15.2
1946 -12.5% -7.0% 17.1
1947 -3.0% 1.6% 15.2
1948 2.4% 4.3% 15.5
1949 -2.3% 0.2% 15.2
1950 6.9% -1.0% 18.4
If you really want to do an apples to apples comparison and want to compare demand versus supply-side stimulus you would compare 1981-2000 (business cycle peak to peak) to 1937-1973 (again peak to peak) In this comparison the effects of the stimulus (WW II and 1981 tax cut), the post-stimulus recession, and the "afterglow" for both periods are considered.
Alternately if you don't want WW II massively affecting your results you would start your comparison well clear of it. This is why I initially chose 1950 and 1980 as my terminal points (Notice the round years ending in zero). Since you put attention on the late 1960's I put in an arbitrary breakpoint in 1965. I chose those specifically to avoid a charge of cherry picking, which you made anyways. A commonly used period is 1947-73 because 1947 is when NIPA data begin. Data before 1947 is reconstructed/estimated by historians.