[ocschwar]

Because in many parts of the US, the major universities were plunked down in a 10km by 10km square of wilderness, with literally nothing else around.

Sometimes a big town grew alongside.

Sometimes it didn't.

Given that universities are non-profits, and therefore are not required to pay any municipal property tax, there were many that simply could not be patrolled by the neighboring towns. So they had to hire their own police forces.

[goalieca]

Ok. So here's an example from Canada. The university of British Columbia technically had its own government. It has to do with the history of the land grant. They have a police force but this police is RCMP (royal Canadian mounted police). They are a federal police force but contracted to smaller towns and cities that don't develop their own. In Ontario many small towns have OPP (Ontario provincial police). Is there a reason why universities simply couldn't contract from a state police force?

[ocschwar]

Historically, land-grant universities predate state police forces. In fact, in most of the US, state police forces are there primarily to enforce traffic safety laws on the highways, because out in the countryside, drivers cross county lines too quickly for the sheriff's police forces to fill that role.

Also, regardless of the formal chain of command for a university police department, the licensing of police officers (i.e. certifying someone as eligible to wear a badge) is a state matter. A university cop doesn't draw his salary from any government, but he can still get his badge taken away by the state if he misuses it.