[Canadian Army]

Here are couple of things to keep in mind:

1.) The average sheriff's department in the United States employs 24.5 sworn officers.

and

2.) Currently their are roughly 58,000 federal law enforcement officers operating throughout the United States and in San Juan, Puerto Rico; who would be available in aftermath of the nuclear attack.

3.) Historically, the sheriff was also commander of the militia in that county. In Twilight you could see the local sheriff or the local State Trooper Commander holding a commission in the State Guard; after all how would the State Guard recruit and screen new members without help of local law enforcement.