Sound Transit's official mission is to develop and deliver a regional public transportation system that improves mobility for the Central Puget Sound. The agency plans, builds, and operates high-capacity transit services across an 1,087-square-mile district encompassing portions of King, Pierce, and Snohomish counties — a three-county region that serves a population well in excess of 200,000 people and is squarely within the CTANW Large Agency category. Service is provided throughout the urban areas of Pierce, King and Snohomish Counties. Transit services include Link light rail; Sounder trains; ST Express Bus; Tacoma Link light rail; and Bus Rapid Transit. Every Link light rail station is ADA-accessible. Sound Transit also provides complementary ADA paratransit service in coordination with its operating partners, serving riders whose disabilities prevent them from using the fixed-route system. The agency's commitment to accessibility runs from station design and elevator maintenance transparency (tracked in real time online), plus trip planning technology and regional coordination with specialized transportation providers.