Based on https://en.wikipedia.org/wiki/Demographic_history_of_the_United_States, it took approx. 140 years for the US to grow to 1 million (1610-1745),
and approx 300 years to grow to a total of 100 million 1610-1915),
and approx 50 more years to reach 200 million 1920-1970),
and only approx 40 years to rise to 300 million (1970-2010),
and which was expected to reach 400 million in less than 35 years (2010-2045)
And sadly, less and less constitute an increase per capita in citizens of Heaven