Write your elected officials and your police chief In your district to implement the 287 G program which can check for legal status if they break the law.
Since the 287g program started in Frederick County 613 people have been arrested and detained at the detention center and questioned about their immigration status Said Capt. Tim Clarke of the Sheriff's Office. Of that 585were deported because they were found to be in the country illegally.
I checked out the sheriff web site for my county and I was not impressed. There are many sheriffs across the country and some of them use their power to the limit as they should, other sheriffs are content delivering subpoenas and transporting criminals. I imagine a sheriff's power is similar to a citizens rights. If you don't exercise them regularly you may loose them.
York Co. PA. Sheriff's web site:
The Sheriff is an elected county official and is an officer of the County Courts, both civil and criminal. The Sheriff or his/her deputies are responsible for serving subpoenas, orders and notices issued by the courts, serving various writs and processes, and provide security in the courtrooms during sessions. He/she is responsible for transporting and securing prisoners to and from correctional facilities within the county and state as well as assisting with extraditions of prisoners (fugitives) apprehended out of state. He/she also transports mental patients and juvenile offenders.