If by the size of government you mean the budget, there have been multiple instances of the government shrinking. As a percent of GDP the 90s saw cuts to federa

If by the size of government you mean the budget, there have been multiple instances of the government shrinking. As a percent of GDP the 90s saw cuts to federal spending, the 2011 sequestration saw a drop in spending even in nominal terms, and obviously the end of WW2 saw a massive collapse in government spending and the end of multiple different programs