Line 5 - Westminster Triangle to Madison Park
Opened as the Madison Line in 1952, Line 5 was known as the "Fishhook Line" colloquially for its long shape extending down upon opening from the city limit at 85th Street all the way down to downtown and its "hook" off of the 27th Avenue Tunnel towards Madison Park. At the time it was planned in the early 1940s, the Lake Washington Floating Bridge via Mercer Island had just been proposed for the first time and the Madison Terminal for ferries was still active and connected only by bus to the rest of the city; much like the Day Street Terminal, a line to the smaller ferry terminal on the mouth of the Montlake Cut made sense. By the time the line opened, however, the Floating Bridge was in her second year across the lake and the terminal would soon be obsolete; the Madison Terminal is now a mixed-use lakeside marketplace and event center surrounded by high-rise condominiums. Nonetheless, the line served an important purpose, connecting the University Park and Cowen Park neighborhoods to the University District, Eastlake and downtown via a line down 10th Avenue, intersecting with the Crosstown Line at 45th and 10th and eventually the Eastlake terminus of Line 8, which opened in 1974 and cut east-west across the north end of Capitol Hill.
An extension of the Madison Line, later Line 5 in the post-1964 reorganization and rebrand, north of 85th street was a major point of debate and controversy for years, much like the extension of Line 3 south of the city. For one, the City of Seattle, which at the time operated the Subway on its own, was reluctant to have to share in revenue or risk with suburban municipalities it regarded as unreliable partners and wanted them to bear the full cost of lines built out of its municipal limits; other than Lake City, many suburbs did not always necessarily see the value of extending the Subway into their own neighborhoods, either, and the city of Soundview, where a Line 5 extension would have gone, had a consistently anti-Subway city council majority and mayoralty for most of the 1970s and 1980s, even as other expansion plans elsewhere went through. The growth of the Soundview Center shopping district and increasingly terrible traffic on Central Avenue and other arterials in Soundview by the early 1990s began to change attitudes, however, but by then a Line 5 extension had fallen down the priority list so that the Eastside Extension and other projects ahead of the 2000 Winter Olympics could be prioritized. Finally, in 1998, a state transportation package identified the 10th Avenue-Pinehurst corridor as one of the most traffic-clogged transit priority corridors in Washington and plans for a Line 5 extension were brushed off, studied and implemented; construction began in 2002 and would finish eight months ahead of schedule in September 2008. A debated extension of Line 5 further into Richmond Center and Richmond Highlands towards the Snohomish County Line has been proposed, but funding and a construction timetable is as of 2023 not in place and it is regarded as a low priority for King County's transit planners.
Starting west of the Dearborn Trunk, the line since 2008 begins under the Richmond city limits at 145th and Pinehurst Boulevard, at the bottom of the neighborhood known as Westminster Triangle. From there, the line goes southeast along Pinehurst Boulevard with a stop near Central Avenue and Haller Lake, then at 125th at the north end of the Pinehurst neighborhood. From there, it turns south on 10th Avenue, following it all the way to the Seattle city limits at 85th, with stops at 100th and Soundview Center, which has emerged as a booming residential and commercial neighborhood since 2008. The line runs all the way to its connection with Line 4 at 45th Street with intermediate stops on 85th and 65th, then has one last stop at Pacific Avenue at the south end of the University District before going through a tunnel under the Montlake Cut to the Eastlake neighborhood, and then passes southwest through Cascade towards Civic Center. Once out of the 3rd Avenue and Dearborn Trunks, it follows 27th Avenue all the way to the Madison Street stop, where it turns off the trunk and exits the tunnel and hill on an elevated guideway down the middle of Madison Street, with a stop in the Madison Park neighborhood before turning into its terminal stop on top of the Madison Terminal.
Line 6 - Capitol Hill Circular
Line 6 was, upon its opening in 1940, probably the most controversial line in the system. An entirely contained 9.6-kilometer loop line under the heart of Capitol Hill that, at the time, had no connection to any other train in the system via a transfer stop. Pilloried as a train to nowhere, it was nonetheless an important part of the Bogue Plan, helping maneuver people around one of the city's most rapidly-emerging neighborhoods without interconnecting with other lines and thus avoiding timing issues. Since its opening, the Circular did get parallel transfer stops with Line 7 starting in 1968 upon its opening, and now is the beating heart of one of the West Coast's most densely populated areas. Due to its closed nature, Line 6 was the first line, in 2016, to get automated rolling stock that does not require a driver; the rollout of such technology elsewhere in the system has been a matter of huge controversy and so far, Line 6 remains the only automated line.
The line runs in a loop, clockwise north to south, from Boston Street in the north down to 15th and then straight south down along 19th Avenue before turning west down Yesler, northwest at Boren and then entirely north again on Broadway all the way back up to Boston Street; on this route, it has stops at Boston Street, Boren Park, Mercer Street, 19th & Pine (where it connects to Line 7), Cherry Street, Pratt Park, Yesler Terrace, James Way, Broadway & Pike (an additional connection to Line 7, in proximity to the Pike Triangle nightlife and entertainment district), John Street, and finally Volunteer Park before finishing the loop back at Boston Street.