http://www.cwc.lsu.edu/cwc/other/stats/warcost.htm

Here's a good source about many aspects of wars America has been involved in. There are numerous pages on important breakdowns and comparisons between the wars. The site is: http://www.cwc.lsu.edu/cwc/other/stats/warcost.htm

II. Casualties

                                    <------------Casualties------------>
                                    [-----Deaths---]                             <-----Percentages-----> Duration 
Conflict                Enrolled    Combat   Other   Wounded     Total    Ratio  KIA    Dead   Casualty   Months  KIA/Month          
Revolutionary War          200.0    4,435   *          6,188      10,623   2.4   2.2%    2.2%     5.3%      80       55
War of 1812                286.0    2,260   *          4,505       6,765   3.0   0.8%    0.8%     2.4%      30       75
Mexican War                 78.7    1,733   11,550     4,152      17,435   1.3   2.2%   16.9%    22.2%      20       87
Civil War: Union         2,803.3  110,070  249,458   275,175     634,703   1.8   3.9%   12.8%    22.6%      48    2,293
           Confederate   1,064.2   74,524  124,000   137,000 +   335,524   1.7   7.0%   18.7%    31.5%      48    1,553
           Combined      3,867.5  184,594  373,458   412,175 +   970,227   1.7   4.8%   14.4%    25.1%      48    3,846
Spanish-American War       306.8      385    2,061     1,662       4,108   1.7   0.1%    0.8%     1.3%       4       96 &
World War I              4,743.8   53,513   63,195   204,002     320,710   2.7   1.1%    2.5%     6.8%      19    2,816
World War II            16,353.7  292,131  115,185   670,846   1,078,162   2.6   1.8%    2.5%     6.6%      44    6,639
Korean War               5,764.1   33,651   *        103,284     136,935   4.1   0.6%    0.6%     2.4%      37      909
Vietnam War              8,744.0   47,369   10,799   153,303     211,471   3.6   0.5%    0.7%     2.4%      90      526
Gulf War                 2,750.0      148      145       467 ^       760   2.6   0.0%    0.0%     0.0%       1      148

Combat deaths refers to troops killed in action or dead of wounds. Other includes deaths from disease, privation, and accidents, and includes losses among prisoners of war. Wounded excludes those who died of their wounds, who are included under Combat Deaths. Ratio is the proportion of wounded in action to combat deaths. Note that the wounded figures do not include cases of disease. Under Percentages, KIA refers to the percent of those enrolled killed in action, Dead to the percent dead from all causes, and Casualty to the percent killed or injured. KIA/Month, killed in action per month, gives a fair indication of the intensity of combat

Notes:
* Non-battle deaths not known for these wars.
+ Confederate non-battle deaths and wounded estimated.
& Actually only six weeks of sustained combat.
^ There was only one month of combat.