The police authorities in the U.S. are not only the "real police", but rather is all that can be subsumed under any prosecution authority, under the name "Law Enforcement "(translated sternly law enforcement) are combined. It depends on what "power" of their authority was granted. If you wanted to capture all equipped with law enforcement authorities in the U.S., it would fill volumes (as it exists in the States).
Discussion
1st Federal Police / State Police
Among the federal agencies include, for example (here a small selection): FBI, U.S. Marshals Service, U.S. Immigration, U.S. Border Patrol, U.S. Coast Guard, CIA, CID (= part of the military police), Military Police, U.S. Air Force Security Police Dept.. of the Mint Police, U.S. Capitol Police, U.S. Congress Police Dept. of Defense Police, U.S. Park Police, U.S. Park Ranger, U.S. Postal Police and U.S. Customs (McCoy, 2009). The 50 states maintain their own police (in the form of Highway Patrol, State Patrol, State Trooper, and State Police) with the exception of Hawaii (where it is the State Sheriff's Department). Furthermore, state police forces are equipped with different powers - they range from slightly too excessively many (Deflem, 2004).
2nd County Police, Sheriff
The individual states are divided into independent administrative counties (districts or circles). Usually operate there (police district) County Police Forces, Police District(Louisiana) or Rural Police (now very rare) or nationals of the County Sheriff's Department (Kappeler & Gaines, 2012). Unless a sheriff presiding over the authority, there is always an elected head of the authority; the rule is not a policeman. Basically, the powers of the district police to catch up where the rights of municipal police forces - namely, at the city limits. Only communities that cannot afford their own police / may want / police administration come with an agreement from the district (McCoy, 2009).
3rd Marshals
As in the previous section, one finds the marshal of the court system. Again, it is not always so. Although more and more disappear Marshal Department, the Sheriff's Department because the tasks are transferred (eg California) - they're still in great numbers (Kappeler & Gaines, 2012). Where a Marshals Office (Department) to a county (district), one can generally assume that it is the "judicial police" these districts. The Marshal is taking court orders and decisions and enforcement of arrest warrants and conducts search operations on behalf of the court (Deflem, 2004).
4th Municipal Police
The municipality has within its city limits on the absolute sovereignty police, which puts them through the ...