America is about to run a pretty wild experiment. And hardly a riskless one. After the nearly $2 trillion American Rescue Plan is passed and signed, Washington will have committed more than $5 trillion in fiscal support since the start of the COVID-19 pandemic. That’s an amount equal to 25 percent of the pre-pandemic 2019 economy. No other country in the world is pumping money into their economy quite like the United States. Even if the ginormous ARP were half or even a quarter of its current size, the economy’s output gap — the difference between where the economy is and where it probably should be based on its underlying potential — would probably be closed sometime this year.