The United States Army in the American Civil War was mostly made up of regiments of infantry and cavalry and batteries of artillery. With the exception of a small number of units from the United States Regular Army, most were organized, armed and equipped by the individual states and taken into national service.

Of the nineteen free states, all but Kansas, California and Oregon sent one or more regiments to the Eastern Theater, although the majority of the men from Ohio to the west fought elsewhere.

Of the slave states that remained in the Union, Missouri and Kentucky sent no troops to the east. Maryland sent units to both sides. Delaware sent several thousand men to the Union army and was the only slave state that provided no organized units to the Confederacy. West Virginia was part of Virginia until the war. But much of it was strongly pro-Union and broke away to become an independent state in 1863.

Select any state from the map or the menu to see information on its regiments and batteries.

Contributions of men and units by each state to the Union army*:

Connecticut	53,721 men	33 regiments and 3 batteries
Delaware	12,280 men	10 regiments and 2 batteries
District of Columbia	15,181 men	3 regiments
Illinois	256,868 men	173 regiments and 35 batteries
Indiana	195,285 men	167 regiments and 26 batteries
Iowa	75,797 men	64 regiments
Maine	65,077 men	36 regiments and 7 batteries
Maryland	42,713 men	24 regiments and 6 batteries
Massachusetts	125,747 men	80 regiments and 48 batteries
Michigan	86,866 men	79 regiments and 14 batteries
Minnesota	24,017 men	14 regiments and 3 batteries
New Hampshire	33,055 men	21 regiments and 1 battery
New Jersey	68,685 men	44 regiments and 5 batteries
New York	413,686 men	316 regiments and 77 batteries
Ohio	309,906 men	249 regiments and 42 batteries
Pennsylvania	323,629 men	291 regiments and 35 batteries
Rhode Island	21,358 men	18 regiments and 10 batteries
Vermont	32,669 men	20 regiments and 3 batteries
West Virginia	32,068 men	27 regiments and 8 batteries
Wisconsin	91,194 men	59 regiments and 13 batteries
United States Regular Army		16 regiments and 60 batteries
United States Colored Troops		175 regiments
United States Veteran Infantry		9 regiments

  *Only states that contributed to the Eastern Theater are shown in the table, but contributions of men and units shown in the table are for all theaters.