With the ideological shift, supported by the intellectual acceptance of Keynes’s General Theory, politicians found themselves with an excuse to do what most had always wanted to do — take more money from the general public and transfer it to favored groups (or voting blocs). The benefits are invariably less than the costs, but they are visible, readily appreciated, and easily credited to politicians. Predictably, beginning in the 1930s federal spending began increasing as a share of GDP. It was about 4 percent of GDP in 1930, increased during the Great Depression and spiked to a historical high of about 47 percent during World War II. The federal government share of GDP then dropped to about 13 percent in 1948, reached a bumpy plateau in the early 1960s at slightly below to slightly above 20 percent that lasted for over 40 years, and then escalated rapidly in late 2008 to an estimated 25 percent in 2011……
The Keynesian Path to Fiscal Irresponsibility | Dwight R. Lee (pdf).