National parks across the country will open to visitors without entry fees during National Park Week April 21-29, and Yellowstone and Grand Teton national parks will be open for the start of the summer season, but with limited visitor services and amenities. Road crews are working to plow snow from roads in both parks, and if weather conditions allow, roads along the west side of Yellowstone National Park will open to automobile traffic on April 20. Visitors will be able to travel by car through the park’s north and west ntrances to Norris, Madison, Canyon and Old Faithful beginning at 8:00 a.m.