National Park Service, Colorado.
Rocky Mountain National Park's 415 square miles (265,807 acres) encompasses a spectacular range of mountain environments. From meadows found in the montane life zone to glistening alpine lakes and up to the towering mountain peaks, there is something for everyone to discover. Along the way explore over 300 miles of hiking trails and incredible wildlife viewing.
Driving from the east: from I-25, take US Hwy 34 or 36. Driving from the west: from I-70, take US Hwy 40 to Granby to US Hwy 34 to Grand Lake. From mid-October until late May, Trail Ridge Road between Estes Park and Grand Lake is closed to vehicles, so driving between the two takes ~4 hours. The closest airport is Denver International (DIA). There is no public transportation between nearby cities and the park.