[ARandomerDude]

> Are there actually random roadblocks within 100 miles of the border where you get stopped

Yes, there's a combination of established locations and "surprise" locations where Border Patrol stops every car on the interstate.

> you...need to provide proof of residency or citizenship?

I don't think they can legally make you produce this unless they have reasonable suspension of a crime. Every time I've been through they have you roll down your window and ask if everyone in the car is a US citizen. Usually there are dogs on both sides of your vehicle while you're asked. I've never had any trouble or had to produce my license.

In this conversation, I only bring it up because I assume when most people see a large police presence, they're nervous that (a) there's probably a reason to need that many police, and (b) what if the police mistakenly believe I'm a criminal? It's just not a pleasant environment, even though I haven't ever been personally hassled at a checkpoint.