Raleigh is known as the "City of Oaks" for its many oak trees. As of the 2000 census, it had a population of 276,093, making it the second most populous city in North Carolina, behind Charlotte. Raleigh, Durham and Chapel Hill make up the three cities of The Triangle, so named in 1959 with the creation of the Research Triangle Park, a research park between Durham and Raleigh (mostly located within Durham County). The Triangle is equivalent to the U.S. Census Bureau's Combined Statistical Area of Raleigh-Durham-Cary. Its total population as of 2004 was over 1.46 million. The estimated Raleigh-Cary metropolitan statistical area population, as of 2004, is 914,680.