As of April 20, 2018, there were 632,219 Indian immigrants and their spouses and minor children waiting for green cards also known as legal permanent residency cards.

https://m.timesofindia.com/business/india-business/indians-w...

Where did you get the 30-40 million number from?

Weird. Why do I keep seeing 4-5 million in the press as the number of people waiting for green cards?

The 30-40 million comes from the fact that there are lot more people who would come to the US that haven't bothered to apply. If you relaxed the criteria the number of applicants would expand.

I'm not anti-immigration (I'm Canadian and we're slightly more relaxed about immigration) but there needs to be some controls in place.

30-40M is the high range of estimated undocumented folks in the US. The more conservative number is 15-20M.

If there are 600K people of Indian descent waiting for Green Cards, then it seems rational there are a few million waiting overall.

You missed my point. I'm hypothesizing current long waiting times is suppressing people applying for US immigration. If you relaxed those standards a lot more people would apply and also get in by those relaxed standards.

You need to be able to "onboard" those immigrants.

All of the anti-immigrant rhetoric makes people vastly overestimate the number of immigrants there actually are, I suspect.

I'm not anti-immigrant. I'm estimating the number of people who would apply if the US stopped queuing and opened their doors.

I didn't say you are, but there is a lot of anti-immigrant rhetoric that purposely overstates the number of immigrants in order to scare people.

Umm.. the green card permanent residents are already here.