The 1Line, formerly Central Link, is a light rail line in Seattle, Washington, United States, and part of Sound Transit's Link light rail system. It serves 19 stations in the cities of Seattle, SeaTac, and Tukwila, traveling nearly between and stations. The line connects the University District, Downtown Seattle, the Rainier Valley, and Seattle–Tacoma International Airport. The 1Line carried over 25 million total passengers in 2019, with an average of nearly 80,000 daily passengers on weekdays. It runs for 20 hours per day on weekdays and Saturdays, with headways of up to six minutes during peak hours, and reduced 18-hour service on Sundays and holidays. Trains are composed of two or more cars that each can carry 194 passengers, including 74 in seats, along with wheelchairs and bicycles. Fares are calculated based on distance traveled and are paid through the regional ORCA card, paper tickets, or a mobile app. Sound Transit uses proof-of-payment to verify passenger fares, employing fare ambassadors and transit police to conduct random inspections. All stations have ticket vending machines, public art, bicycle parking, and bus connections, while several also have park-and-ride lots. Voters approved Central Link in a 1996 ballot measure and construction began in 2003, after the project was reorganized under a new budget and truncated route in response to higher than expected costs. The light rail line, which followed decades of failed transit plans for the Seattle region, opened on July 18, 2009, terminating at in the Downtown Seattle Transit Tunnel and near Sea–Tac Airport. It was extended south to in December 2009, north to the University of Washington in March 2016, and south to Angle Lake in September 2016. The line was temporarily renamed the Red Line until its designation was changed to the 1Line in 2021, coinciding with an extension to Northgate. Further extensions to Lynnwood and Federal Way are planned to open in 2024 and 2025, respectively. The 2 Line will open in 2023, connecting Seattle to the Eastside suburbs and forming a multi-line network via its connection with the 1Line. Further expansion under Sound Transit 3 will divide the current corridor between two lines, the 1Line from Ballard to Tacoma and the 3 Line from Everett to West Seattle. History Background and early transit proposals Public transit service within Seattle began in 1884, with the introduction of the city's first horse-drawn streetcar line. The system had been replaced with a