I am sure I saw a question about these in a thread I was reading but I cannot now find it, so I ask for leniency in making the results I came across whilst looking for something else. I forsee a problem with the table...
American Casualties
Reports on American casualties sustained during the expedition differ considerably but no evidence has been found of a War Department calculation as to the actual number. Consolidated regimental returns show 66 casualties. However, there are no returns for 9 March or 21 June, the dates of the Columbus and Carrizal attacks. War Department Annual Reports give 76 casualties, which includes those sustained at Columbus but does not include 2 killed and 7 wounded in subsequent encounters with Villa’s forces. The Southern Department surgeon reported 43 men died of wounds received in action during the fiscal year 1916, which undoubtedly may be interpreted to mean that these men were casualties of the campaign into Mexico. All reports agree that only two officers were killed.
1) 9 K; - W; -M; 11 Cap; 24 Accidents etc; 33 Died of Disease; 66 Total
2) 26 K; 25 W; 1 M; 24 Cap; - Accs; - Disease; 76 Total
1) Consolidated Returns Mar-June 1916; 2) WD Annual Reports 1916
Mexican Casualties
On the Mexican side, no reliable figures are available. Based on reports of encounters with the Villistas, it is estimated that well over 200 were killed or wounded.
Prisoners were taken from time to time but because of lack of means to guard them or inability to distinguish between Villistas and Carranzistas, they wore often released. If evidence seemed justifiable, they were held. When Pershing was preparing to return to the US he sent twenty-one Mexicans to Columbus to be held pending decision by the State Department. These prisoners were alleged to have been connected with the Columbus raid.
Losses among the Carranzista forces are variously estimated as from 50 to 100 killed , but no figures are found showing the number wounded.
From THE MEXICAN PUNITIVE EXPEDITION under Brigadier General John J Pershing United States Army 1916 - 1917 Robert S Thomas and Inez R Allen at http://cgsc.contentdm.oclc.org/cdm/sing ... 768/rec/14