Police agencies in the US are wildly different from basically everywhere else (except Canada kind of). There are no centralized federal police. There are state, county/parish and local police agencies and all have different duties. State is strictly highway patrol in most places. County (sheriff’s department) usually manages jails, courthouses, schools, public events, SWAT and other special needs. Local is your basic patrol and 911 response force. In large cities the local cops do a lot of the usual work of county police too. Funding, staffing and general accountability can vary drastically between any one agency. Sheriffs and police chiefs have enormous power.