That + killing/imprisoning a lot of your own population + creating an economic climate where it was hard to sustain your family + creating a political climate favoring emigration?
https://en.wikipedia.org/wiki/Demographics_of_the_Soviet_Uni...
Compare with the US:
https://en.wikipedia.org/wiki/Demographics_of_the_United_Sta...
And population growth in the pre-WW1 Russian Empire was even higher, despite having regular food shortage and hunger period. In general, pre-industrial agrarian societies tend to have much higher birth rates than industrial and post-industrial ones.
For some strange reason the US nowadays is comparable in the percentage of prisoners in USSR in worst Gulag years:
https://en.wikipedia.org/wiki/Comparison_of_United_States_in...
I don't have an explanation here, TBH. The US is a rich and socially advanced country. In comparison to Europe this feels very wrong.
The US justice system is very broken. No matter where one stands politically (e.g. be more lenient or be tougher on crime), the current system is suffering from bureaucracy, ineffectiveness, ineptitude and slowness. It's caught in an endless feedback loop.
> killing/imprisoning a lot of your own population
the US has the highest incarceration rate in the world
> creating an economic climate where it was hard to sustain your family
the cost of housing has far outgrown the median household income and in many places you need 2+ income earners to sustain a household meaning nobody has time to raise children