If this is the wrong subreddit please point me to a more appropriate one. At first I thought this was another Mexican revolution era photo but it has a more sepia tint, older style of facial hair, and a lack of the usual plethora of bandoleers, I think he may be a rurale or other militia member. My interest is that I collect Mexican swords and have one that is a twin to the one he carries and am trying to establish a date for it.
If you're really after the date of your sword, maybe add a photo of that also: there are several sword/weapons buffs in here
The facial hair is much more typical of the fashions of the 1850's-60's, if it was the USA or Europe. Mexico, however, is another matter. Though it is easy to think of him as imitating the French soldiers of Maximilian, that's a big jump.