In the Emerald City, it's not just the name that's green. The City of Seattle is known for rain-fed lush greenery but also for its environmentalism. It uses a charter form of government, which features an elected mayor and city council along with a city attorney. The nine council members are elected at large annually. Among some 25 other departments, Seattle has an Office of Sustainability and Environment, it's restoring salmon habitat, and it celebrates Earth Month rather than just Earth Day. The city serves a population of more than 600,000 with an annual budget of around $4 billion. It was first settled by Europeans in 1851, and takes its name from Chief Seattle, a local tribal leader.