1. The State of New York with 448,850 and Pennsylvania with 337,936 Union soldiers aggregated 768,635 soldiers and outnumbered the entire Confederate army.
2. Illinois with 259,092, Ohio with 313,180 and Indiana with 196,363 soldiers aggregated 768,635 soldiers and outnumbered the Confederate army.
3. New England with 363,162 and the 316,424 Union soldiers of the slave States aggregated 679,586 soldiers and outnumbered the Confederate army.
4. The States west of the Mississippi River, exclusive of Missouri and the other Southern States, enlisted 319,563, Delaware, NewJersey, and the District of Columbia 105,632, and the negro troops enlisted in the Southern States and not before counted were 99,337 an aggregate of 514,532 soldiers.
These facts, taken from the war records, show that there were four Union armies in the field, each of which was as large as the Confederate army.
From the book: History of the Fourth Tennessee Cavalry by Adjutant George B. Guild.