Yes, Laurie is right, I forgot about the road construction. There was road construction when we were there in late May of this year from Madison to Norris which could cause 15 to 30 minute delays in both directions. They appeared to be putting in a nice turnout and bridge just a few miles north of Madison on that road and had a one lane dirt/gravel road with some workers controlling the traffic.
The road going north to Norris from Madison was actually closed at the Madison junction during the hours from 10:00pm to 8:00am when we were there. Not sure when they are scheduled to complete this work or if they have already done so but it looked like it could have gone on several months based no what they were doing.
There was also road construction at the very north end of Grand Teton Park with the speed limit at 35 miles/hr in places.
I really liked both national parks. Tetons has amazing scenery (those moutains are so pretty, especially at Oxbow bend, and along park road) but to see the wildlife close up we had to get up early in the morning to go out and were not disappointed (saw moose, elk, bison right along the side of the road, and a grizzly around the Oxbow bend area).
On the otherhand Yellowstone seemed to have wildlife at all times of the day and close up In Yellowstone along the West Enterance to Madison, Madison to Old Faithful, and Canyon to Fishing Bridge, the Bison are very prevalent and many times they were very close to if not walking right in the road). Also saw elk and a black bear during the afternoon one day and a coyote another day. Yellowstone also has so many geothermal features which was really cool (although I wish I had been able to see Grand Prismatic springs without the steam cloud obscuring it). You have the Upper, Midway , Lower Geyser basins, Norris Geyser Basin, and Mammoth Hot springs, etc.
Greg