Transportation in Seattle is largely focused on the automobile like many other cities in western North America; however, the city is just old enough for its layout to reflect the age when railways and trolleys predominated. These older modes of transportation were made for a relatively well-defined downtown area and strong neighborhoods at the end of several former streetcar lines, now mostly bus lines. Due to Seattle's isthmus-like geography and the concentration of jobs within the city, much of the flow of transportation in the metropolitan area is through the city proper. North-south transportation is highly dependent on the Interstate 5 corridor, which connects the Puget Sound area with southwest Washington cities and the Portland metropolitan area, as well as cities to the north such as Bellingham and Vancouver, Canada. I-5 continues as British Columbia Highway 99 at the U.S.-Canada border's Peace Arch crossing, between Blaine and Surrey. State Route 99 is also a major arterial in the western half of the city; it included the now-defunct Alaskan Way Viaduct along the Seattle waterfront. The Alaskan Way Viaduct replacement tunnel was opened in place of the elevated viaduct in February 2019 on account of seismic instability. Transportation to and from the east is via State Route 520's Evergreen Point Floating Bridge and Interstate 90's Lacey V. Murrow Memorial Bridge and Third Lake Washington Bridge, all over Lake Washington. Those bridges are respectively the first, second, and fifth longest floating bridges in the world. State Route 522 connects Seattle to its northeastern suburbs. Two public transportation agencies serve Seattle: King County Metro, which operates local and commuter buses within King County, and Sound Transit, which operates commuter rail, light rail, and regional express buses within the greater Puget Sound region. In recent years, as Seattle's population and employment have surged, transit has played an increasingly important role in transportation within the metro area. By 2017, nearly 50% of commuters to downtown Seattle arrived via mass transit. Unlike most North American cities, water transportation remains important. Washington State Ferries, the largest ferry system in the United States and the second largest in the world, operates a passenger-only ferry from Colman Dock in Downtown to Vashon Island, car ferries from Colman Dock to Bainbridge Island and to Bremerton, and a car ferry from West Seattle to Vashon Island to Southworth. Seattle was once home to the Kalakala, a streamlined art deco-style ferry that