Secrecy News today published a Congressional Research Service study of U.S. war casualties.
The compilation is intended for use by MCs and the methodology is completely obscure - the only thing these numbers have going for them is the imprimatur of the CRS.
Quick and dirty comparison:
Wikipedia - Union KIA, 110,000; 275,200 wounded
Infoplease - Union KIA, 140,414; 281,881 wounded; 224,097 other deaths in service
New CRS study - Union KIA, 138,154; 280,040 wounded; 221,374 other deaths