The discovery of gold in California in 1848 brought a heavy demand for passage to the gold fields, with the main routes crossing disease-ridden Panama to avoid a very long slow sailing voyage around all of South America. A railroad was built that carried 600,000 passengers but the disease threat remained. A canal in Nicaragua was a much more healthy and attractive possibility, and American businessmen gained the necessary permissions, along with a U.S. treaty with Nicaragua. However the British were determined to block an American canal, and seized key locations on the Mosquito Coast on the Atlantic that blocked it. The Whig Party was in charge in Washington and unlike the bellicose Democrats wanted a business-like peaceful solution. The United States decided that a canal should be open and neutral to all the world's traffic, and not be militarized. Tensions escalated locally, with small-scale physical confrontations in the field. Washington and London found a diplomatic solution. The Clayton–Bulwer Treaty of 1850 guaranteed equal canal rights to both the U.S. and Britain. Each agreed not to colonize Central America. However, no Nicaragua canal was ever started.