There are 32 public transit agencies in Washington state, which serve rural, small urban, urban and regional areas. Eighty-four percent of the state's population lives within the boundaries of a transit district. For detailed information on public transportation statewide, see the Washington State Summary of Public Transportation . Passenger trips: Passenger trips are the total number of single passenger trips boardings. A passenger trip may not be an individual's full commute. For example, throughout their commute, an individual may transfer from one bus to another, or transfer from one mode to another (for example, from a ferry to a bus). Regardless of transfer or change in mode, each boarding is counted as a single passenger trip. Percentage of workers who commute to work by public transportation: Commuting by public transportation makes up a greater share of trips in larger metropolitan areas. People use many different modes of transportation — sometimes in combination — to get to and from work. Vanpools: Vanpool programs provide safe, reliable vans so groups can commute together. Washington has the largest public vanpool fleet in the nation. Each weekday, more than 18,000 commuters ride in more than 3,000 vanpools across the state. Vanpools help to reduce single occupancy vehicle trips, improving air quality and reducing greenhouse gas emissions by reducing the number of cars on the roads.