The chart below shows the current enlisted rank insignia of the United States Army, with seniority, and pay grade, increasing from right to left. The enlisted ranks of corporal (E-4) and higher are considered non-commissioned officers (NCOs). The rank of specialist is also in pay grade E-4, but does not hold non-commissioned officer status; it is common that a soldier may never hold the rank of corporal, and instead be promoted from specialist to sergeant, attaining junior NCO status at that time.
In the beginning, U.S. Army enlisted rank was indicated by colored epaulets. The use of chevrons came into being in 1821, with the orientation changing over time from point-down to point-up and back again, to the point-down orientation seen in the American Civil War. Around the turn of the 20th century, point-up wear of chevrons returned and has remained so.
History
1775–1821: epaulets
From the creation of the United States Army to 1821, non-commissioned officer (NCO) and staff non-commissioned officer (SNCO) rank was distinguished by the wearing of usually worsted epaulets.
From 1775 to 1779, sergeants and corporals wore one epaulet on the right shoulder, corporals of green color, sergeants of red color.
In 1779, (SNCOs) were authorized two silk epaulets, sergeants two worsted and corporals one worsted on the right shoulder. The color was white (infantry), yellow (artillery), or blue (dragoons). In practice it seems the prescribed blue epaulettes for cavalry NCO never came in wide use while the wearing of white epaulettes prevailed.
By 1783/84, the Continental Army was discharged. For a few weeks, only 55 artillerymen at West Point and 25 men at Fort Pitt were to remain. In August 1784, the 700 men strong First American Regiment (including two companies of artillery) was organized as kind of an army substitute. In October 1786 by approval of Congress, this force should expand to a Legionary Corps of additional infantry, rifle troops, artillery, and dragoons. But this project never materialized. In 1791, the Second Regiment of Infantry was raised and organized as the First Regiment. Both units amalgamated in 1792 with the Legion of the United States, including artillery and dragoons (the first federal mounted force since the discharge of the Continental Light Dragoons in 1783), that then transformed into the US Army in 1796.
Uniform regulations dated January 30, 1787 prescribed, SNCOs wore two silver silk epaulets, sergeants two worsted and corporals one worsted. In the same year, the epaulets' color of cavalry NCOs officially changed from blue to white. At that time the federal mounted force of two troops of dragoons existed only on paper and never got beyond the planning stage (see above).
In 1799, red worsted epaulets were prescribed for all NCOs in all branches: SNCOs on both shoulders, sergeants on the right shoulder, corporals on the left. Chief musicians were identified by two white epaulets. Shortly after, in the year 1800, the color of the epaulets was changed to yellow, for chief musicians in to blue. In reality, the artillery NCOs ignored the order of 1799 and maintained their yellow epaulets, as did a company of bombardiers, sappers, and miners recruited during the War of 1812. In 1802 the infantry NCOs switched back to their former white epaulets. By 1808 dragoons were wearing white and riflemen yellow. SNCOs probably wore two worsted epaulettes with crescent, sergeants two plain worsted epaulettes, and corporals wore one epaulette on the right shoulder. Sergeants were given two epaulets once again in 1812.
1821–1832: chevrons and "wings" vs. epaulettes
From 1821 to 1832, enlisted personnel wore dark blue "wings" trimmed in yellow (infantry, in white) on each shoulder and a horizontal row of four yellow (infantry, white) buttons on each cuff. This precluded the use of epaulets. Rank was shown by a single, point up, chevron. Sergeants major and quartermaster sergeants wore the chevron on both upper sleeves, principal musicians and sergeants on both lower sleeves and corporals on the right upper sleeve. The chevrons were yellow for artillery and white for infantry. The regulations prescribe black chevrons for riflemen but that regiment had been abolished.
In 1825 this system was changed. Sergeants major, quartermaster sergeants and principal musicians now wore a chevron and an arc on both upper sleeves, sergeant a chevron on both upper sleeves and corporals a chevron on both lower sleeves.