to the route numbers, although there are clusters in certain neighborhoods. Suburban routes follow a numbering system: 100–199 for South King County, 200–299 for the Eastside, 300–399 for North King County, and 900–999 for dial-a-ride and custom routes. The in-city routes with the highest ridership are the RapidRide D Line from downtown to Crown Hill via Uptown/Seattle Center and Ballard; the 7, traveling from downtown through the International District to the Rainier Valley; the 40, traveling from downtown through South Lake Union, Fremont, and Ballard to Northgate; the RapidRide C Line from South Lake Union and downtown to West Seattle's Alaska Junction and Westwood Village; the 36, traveling from downtown through the International District to Beacon Hill; the 5 from downtown via the Woodland Park Zoo and Greenwood/Phinney Ridge to Shoreline Community College; the 44, a crosstown route connecting the University District and Ballard; the 8, a crosstown route connecting Uptown/Seattle Center and South Lake Union with Capitol Hill, the Central District and Mount Baker; and the 70, connecting downtown to South Lake Union, Eastlake, and the University District. The Metro-operated Seattle Streetcar routes are numbered in the 90s, with the South Lake Union Streetcar numbered 98 and the former bus replacement for the Waterfront Streetcar numbered 99. The suburban system is more numerically organized. Roughly speaking, areas in South King County (from Burien and Des Moines through Renton and Maple Valley) are served by routes numbered in the 100s, areas in East King County (from Renton to Bothell) are served by routes numbered in the 200s, areas in North King County (from Bothell to Shoreline) are served by routes numbered in the 300s. The Metro-operated Sound Transit Express routes are numbered in the 500s. Route numbers in the lower 900s (901–931) are used for Dial-a-Ride services, while shuttles connecting to the King County Water Taxi are numbered in the 700s. Other shuttle services, including Via in the Rainier Valley, are contracted out to private operators. Since 2003, Metro has contracted with senior charities to operate the Hyde Shuttle system, which provides free rides to elderly or disabled passengers in Seattle and other cities. Metro formerly funded a shuttle system named Ride2 that served West Seattle and Eastgate using contracted private buses, which ended in 2019. Metro is contracted to operate special custom buses. Custom routes that serve schools in Bellevue and on Mercer Island are numbered in the 800s