In the United States Navy, the United States Coast Guard, the United States Public Health Service Commissioned Corps, and the National Oceanic and Atmospheric Administration Commissioned Corps, commander (CDR) is a senior officer rank, with the pay grade of O-5. Commander ranks above lieutenant commander and below captain. Commander is equivalent to the rank of lieutenant colonel in the other uniformed services.
A Commander in the U.S. Navy may command a frigate, destroyer, submarine, aviation squadron or small shore activity, or may serve on a staff (typically as executive officer). An officer in the rank of commander who commands a vessel may also be referred to as "Captain" as a courtesy title, or informally referred to as "skipper."
Historically, the rank of "Commander" was originally called "Master Commandant" in the U.S. Navy. This rank corresponded in function to "Master and Commander" in the Royal Navy. It was later changed in 1838 to its modern form.
The Rochester (NY) Police Department (RPD) uses the rank of Commander. Higher than Captain and below Deputy Chief, the rank is achieved by appointment. Commander is the rank held by the two patrol division heads and other Commanders fill various administrative roles. The St. Paul Police Department (MN) is another police force that uses the rank of commander. In the St. Paul Police department, Commanders serve as the chief of the district/unit that they oversee.
Many police departments in the Midwest use the rank of commander. It is equivalent to a lieutenant in most other departments, being above a sergeant and below a deputy chief or captain.
Commander is also utilized by larger Sheriff's Departments in the United States. The rank usually falls between Chief Deputy and Captain, which is three positions removed from the sheriff.
A numbered air force commander is normally a Lieutenant General, although some may be in the rank of Major General, especially in the Air Force Reserve or Air National Guard. The MAJCOM commanders are normally in the rank of General or Lieutenant General.