Mostly Southwest Wyoming, though there are amazing sites in Northwest Wyoming as well, just as the Dinwoody and Medicine Wheel sites.
People ask me all the time: What do they mean? Short answer: We don't know. There are a variety of reasons people make pictures. For decoration, to make the place special, to make the area holy, or because the area is holy. Special places are made or recognized by Native Americans then are used as "libraries", or a place to store cultural and historical knowledge (All other cultures do this, to. Churches are a good example).
Some of the petroglyphs in Wyoming do have known meaning, as they are made relatively recently by cultures are still intact today. But many groups, having been mistreated by government actors in the past (and unfortunately still today), are not willing to discuss the meaning of their historical petroglyphs with anthropologists. This is akin to many religious groups not being willing to discuss certain details of their beliefs with outsiders.
So, when you visit these sites, be respectful. Obey all federal and state regulations. DON'T TOUCH. Don't assume you can take pictures, check first. Try to engage with the local culture, especially if there is an interpretive center nearby. Consider the oppression these peoples had to go through, and be grateful that some of these cultures are still around today.
Check out Wyoming State Historical Society – www.wyohistory.org and Sacred Destinations – www.sacred-destinations.com for more information on how to access these amazing sites.
Where have you been? What have you seen?