Master trooper is a rank used by several state police agencies within the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and in some world militaries.

In particular, in the Louisiana State Police

Louisiana State Police

The Louisiana State Police is the state police department of Louisiana, which has jurisdiction anywhere in the state, headquartered in Baton Rouge. It was created to protect the lives, property and constitutional rights of people in Louisiana. It falls under the authority of the Louisiana...

, in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, it is a rank below sergeant

Sergeant

Sergeant is a rank used in some form by most militaries, police forces, and other uniformed organizations around the world. Its origins are the Latin serviens, "one who serves", through the French term Sergent....

, yet above senior trooper

Senior Trooper

Senior trooper is a rank used by several state police agencies within the United States and in some world militaries.It is the third class in the progressive series of state trooper ranks. It is a step below master trooper, yet above trooper first class...

. The insignia for this rank consists of a gold colored 'MT' collar pin worn on the wearer's right lapel. Troopers who complete fifteen (15) years of satisfactory or exceptional service are promoted to the rank of master trooper. The title of address is "master trooper".

Usage in other agencies or countries may vary.