The National Oceanic and Atmospheric Administration Commissioned Officer Corps (informally the NOAA Corps) is one of eight federal uniformed services of the United States, and operates under the National Oceanic and Atmospheric Administration (NOAA), a scientific agency overseen by the Department of Commerce.

[18][17] Should it be called into active duty, it would be a department of one of the six branches of the United States Armed Forces.

[19] The NOAA Commissioned Officer Corps traces its roots to the United States Coast and Geodetic Survey, the oldest scientific agency of the federal government.

Since most men of the Survey had Union sympathies, most stayed on with the Survey rather than resigning to serve the Confederate States of America; their work shifted in emphasis to support of the United States Navy and Union Army, and these Coast Surveyors are the professional ancestors of today's NOAA Corps.

[18][20] With the outbreak of the Spanish–American War in April 1898, the U.S. Navy again withdrew all of its officers from Coast and Geodetic Survey assignments.

They returned after the war ended in August 1898, but the system of U.S. Navy officers and men crewing the Survey's ships that had prevailed for most of the 19th century came to an end when the appropriation law approved on June 6, 1900, provided for "all necessary employees to man and equip the vessels," instead of U.S. Navy personnel.

The law took effect on July 1, 1900; at that point, all U.S. Navy personnel assigned to the Survey's ships remained aboard until the first call at each ship's home port, where they transferred off, with the Survey reimbursing the Navy for their pay accrued after July 1, 1900.

[21] From July 1900, the Coast and Geodetic Survey continued as an entirely civilian-run organization until after the United States entered World War I in April 1917.

[18] To avoid the dangers that Coast Survey personnel had faced during the Civil War of being executed as spies if captured by the enemy, the United States Coast and Geodetic Survey Corps was established on 22 May 1917, giving Coast and Geodetic Survey officers a commissioned status so that under the laws of war, they could not be executed as spies if they were captured while serving as surveyors on a battlefield during World War I.

The creation of the Coast and Geodetic Survey Corps also ensured that in wartime a set of officers with technical skills in surveying could be assimilated rapidly into the United States Armed Forces so that their skills could be employed in military and naval work essential to the war effort.

[18] The Coast and Geodetic Survey Corps returned to peacetime scientific pursuits after the war.

Over half of all Coast and Geodetic Survey officers were transferred to the U.S. Army, the United States Army Air Forces, the U.S. Navy, or the U.S. Marine Corps, and deployed in North Africa, Europe, the Pacific, and the defense of North America as artillery surveyors, hydrographers, amphibious engineers, beachmasters (i.e., directors of disembarkation), instructors at service schools, and in a wide variety of technical positions.

The ESSA Corps retained the responsibility of providing commissioned officers to operate Coast and Geodetic Survey ships and of providing a set of officers with technical skills in surveying for incorporation into the U.S. armed forces during wartime.

[57] The flag is displayed in accordance with the customs and traditions of the uniformed services of the United States.