Yellowstone and Glacier in May

We went in May 2016. Daytime temps were high 50's low 60's. At night it got into the high 30's. We had no snow although there was snow on the ground in some places with higher elevations. Not everything was open but there was still plenty to see. We stayed in Madison Campground. No hookups but you can run a generator during the day. We came across a mother grizzly and 3 cubs right on the road going from Norris to Canyon. Crowds are light that time of year. We live near Reading,Pa so you will probably take a similar route. We went I 70. In Illinois we took I-74 to Missouri Rt 36 which runs across the whole state. It is 4 lanes and 65mph. Pershing State park is right off Rt 36. We paid $23 a night in 2016 with electric hookup. Then we hit I-29 north to Nebraska Rt 6 to I-80. Yellowstone's southern entrance wasn't open when we arrived so wen went in through West Yellowstone. South entrance was open when we left. If you like old cars, trucks, tractors,motorcycles or history in general,I would suggest the Harold Warp Museum in Minden, Nebraska. They have a campground and if you stay overnight, you get one fee ticket to the museum Plan to spend several hours there. On the way back we stayed at Buck Creek Lake State Park in Ohio. It;s about 10 miles north of I-70 but very nice with electric hookups. It was $26 a night at that time.