In Missouri this year it's a two buck limit. You can take one during firearms season and alternative methods combined and one during archery season. Or you can take two during archery season but you're only allowed one before firearms season. After November firearms is over you could conceivably take two bucks with a bow if you haven't tagged any yet. Some areas also have antler point restrictions.
Used to be three - this year is the first year with a two buck limit. I took a small buck early and am antlerless deer only until firearms season. I have one antlered deer tag left to use either during firearms season or the second half of archery season.