The roadway would be physically blocked and enforced with armed guards. If you're not identifable as a resident or it's necessary for you to proceed, you'll be turned back. We have Black residents, so don't start with that. A carload of young males, White or Black, will be turned back. (Unwanted wanderers)
We have a core group of friends and neighbors that are preparing/prepared and discussing these sort of things on a regular basis not in a meeting but as we're together (one on one) on a weekly basis
I live on a road that leads to beautiful white beaches and then dead-ends there. Only the people living on dead-end roads will be allowed to pass.
The boundries will be defined by easy to defend check points...a stream/creek with a bridge over it..you can't go around, etc. We have neighbors with bull dozers, back hoes and etc. My neighbor has a large landscaping company with large fuel tanks, 1,000 gallons of diesel and regular gasoline, he keeps those full these days.
I don't know what we'll do with obviously 'good' people in desperate need (especially with children) who show up begging. I've already been told that I won't be manning a blockade..."you're to soft hearted, Bill."
Now, mind you, this all assumes that law enforcement has broken down or has been overwhelmed which we worry will happen at some point...any government agency that maintains/restores law and order will be obeyed...we don't plan to fight the government unless they come to confisticate (bullies) our supplies for re-distribution. We define 'bullies' as anyone with designs on our supplies or contrary to our well-being.
Flexability and mature judgement are necessary skills.