Fodor's Travel Talk Forums - driving time from Mammoth Springs to Jackson

The distance from Mammoth to the Jackson Hole Aiport is considerable, particularly when you consider the conditions. (The aiprport is about 10 miles north of Jackson itself) The distance is about 140 miles, but there are several factors to consider.
1. You are going through Yellowstone where traffic can be very slow at times, therefore a time estimate of close to 4 hours is not unreasonable.
2. The road in Yellowstone from Tower Falls to Canyon is closed. All south bound traffic from the northern section of the park MUST take the route through Mammoth south to near the Norris Geyser Basin -- Norris Junction.
From Norris you can either turn east over to Canyon and then south to the lake and on to the south gate, or you can go by way of Old Faithful. I think the Old Faithful route is shorter, but the road between the Norris Geyser Basin and Madison Junction is subject to delays because of construction.
The same is true of the other route in the Haydn Valley area. So right now there is no way to tell which route might catch you in a delay of 30 minutes.
3. None of the roads are high speed, and traffic can be heavy depending on when you attempt to make the drive. The earlier in the morning, the better you are.

Given the airport security measures that could take you an hour or so, and the risk of delays enroute, and the fact that that you do not want to miss your flight (better half an hour early than 2 minutes late), I suggest that you allow at least 5 hours from the time you leave Mammoth until your flight is scheduled to leave.
I personally would leave early, before 7 AM, and allow 5.5 hours. I prefer to wait at the airport, snoozing, than to be running up my blood pressure breaking the speed limit to get there.
There is some uncertainty here and there are factors that you cannot control.