From Jackson, Wyoming head north on Highway 191/89. Just past the boundary of Grand Teton National Park take the first right at the traffic circle onto Gros Ventre Road. The campground and the town of Kelly are several miles down the road. Moose can be spotted anywhere along the river which parallels the road.
The stretch of river behind the Gros Ventre Campground is always a good place to find moose. I always stay in the campground for this reason. If not staying in the campground, follow the campground rules for visitors which usually requires you park at the amphitheater parking lot and walk in.
During the fall rutting season the Gros Ventre River, just north of Jackson, Wyoming and along the southern boundary of Grand Teton National Park, is teaming with moose. As the river nears the park campground and the small isolated community of Kelly, it runs through a forest of willows and cottonwoods which in a good year are full of autumn yellows. This dominant bull moose decided to walk straight through the campground one morning while many of the campers were still in bed. On his way through he stopped in front of this patch of cottonwoods displaying their full autumn yellows. He paused for several seconds, seeming to want his picture be taken, before continuing his way to the end of the campground and into the willows along the river.