...put limits on how many people are allowed to immigrate.

I don't know what the actual numbers are, but:

If 20 million people want to come into this country, and the US only allows 500,000 a year to immigrate, there will of COURSE be a backlog.

I guess there are people who think the US should just let as many people as want to immigrate?

I wonder how long people think it takes for someone to legally immigrate into OTHER countries?