He renewed his interest in the peoples of the Pacific Northwest at this time, and over the next 15 years made numerous field trips to Vancouver Island and other parts of the northern Pacific coast. In 1894 he joined the newly founded Field Museum in Chicago, and after a year took a job at the American Museum of Natural History in New York. During the years of his work for museums, Boas worked out his ideas on culture history and contact and principles for ethnographic categorization and display. His views, and generally his arguments against the prevailing "cultural evolution" model of ranked cultural types, referred to above, always brought him into conflict with the higher-ups of the museum hierarchy, and in 1905 he resigned from the American Museum, leaving behind museum work for good.