Immigration saves the US as it is able to mechanically increase real GDP just by population growth. The labor force growth drives inflation up as it was in the late 1960s and 1970s (women changed the rate of participation in labor force from ~50% to 80-90% just within one decade). The Fed has the only tool to put the rate of price inflation down - increase the overnight rate. As the real GDP has been growing in the previous couple of years mainly due to mechanical population increase (the population growth rate is back to 1.5% per year as in the 1990s) , there overnight rate does not have the same growth suppressing effect as with the population growth of 0.5% per year observed in 2010s. Overall, the immigration idea is genius and there is no recession threat before the immigration stops. The economic model and equations behind these processes are here.