Boulder is a city in the state of Colorado, in the U.S.A. it has mountains to the west, called the Flatirons, which are part of the Rocky Mountains. A river named Boulder Creek runs through the city. The population is around 100,000. Boulder has cold winters,and it is often very snowy. It has warm, sunny summers. In the past, the main industry was mining. Today, the city is better known for its academic life, its healthy lifestyle, and its culture. the main things to see and do in Boulder include hiking in the mountains, visiting the Boulder History Museum, and going shopping in the historic downtown neighborhood.