Welcome to Rocky Mountain National Park. The vast Rocky Mountains range extends from the western United States up to Canada. National parks in both countries protect many of the huge peaks. Here in Colorado, Rocky Mountain National Park covers about 1,100 square kilometers. Although it is much smaller than other western parks, like Yellowstone, it welcomes almost as many visitors each year. People from around the world come to experience its alpine, or high-mountain, environment. In the spring and summer, wildflowers burst to life and many kinds of butterflies arrive. In the fall, the aspen trees turn bright yellow and orange. In the winter, deep snow blankets the park. Its peaceful alpine lakes freeze over.