It's a tale of two subways, so built up in the transit mythology of their respective cities. Both have been in the works for almost a century, and have endured changes in plans, false starts, and "future-proofing" of other transit infrastructure that was fortunate enough to be carried to completion.

On January 1, 2017, phase one of New York's Second Avenue Subway opened to the public, ending a century of "almost, but not quite" for the residents of the Upper East Side of Manhattan. "The Line That Time Forgot" will provide an alternative route for an estimated 200,000 people each weekday, many of whom count themselves among the 1.3 million riders who currently pack onto the Lexington Ave Subway's 4,5,6 trains on a daily basis, making it the most heavily used rapid transit line in the United States.

The parallels between the Lexington Subway and the Yonge Subway are not hard to draw. However, the opening date for Toronto's equivalent, the Relief Line (formerly the Downtown Relief Line, formerly the Queen Street Streetcar Subway) is still TBD, tentatively projected sometime between 2028 and 2031.

The $4.4 billion (USD) project will complete the first 2 miles (3.2 km) of what will become an 8.5 mile (13.7 km) subway running nearly the entire length of the east side of the island of Manhattan, most of it under Second Avenue. The phase just opened includes 3 new stations and an expansion to an existing station.

New York City's updated subway map, showing the Q Line using the Second Avenue Subway

The project was initially proposed in 1919 as a replacement for the Second Avenue Elevated line, but the Great Depression put the first of many halts to that project. The Elevated was removed in 1942, but no subway line replaced it. The project was revived again in the 1960s, and a construction began in 1972 at Second Ave and 103rd St, in 1973 it began in Chinatown, and in 1974 in the East Village, the latter two both being on the Lower East Side. But with the City facing near-bankruptcy in the mid to late 1970s, construction on the line was slowed substantially, and was eventually halted in 1978.

It would not be until 2003 when preliminary funding for the subway was once again approved, with full funding for Phase 1 not coming until 2007. The four phase, full build-out would make use of all the segments built in the 1970s, although only the section built on the Upper East Side would be used by Phase 1.

Toronto's "Line That Time Forgot" has had a similar roller coaster history. Initially proposed in 1910 as a streetcar subway, the line remained on the shelf until the 1944 plan that was to see the Yonge Subway and Queen Streetcar Subway built in sequence. Ultimately, only the Yonge Subway was built.

The Queen Subway was then revived in a different form, as part of an east-west subway that would utilize Bloor Street and Danforth Avenue on the outer ends, but Queen St through the core. Ultimately, a straight shot across those two streets was chosen, and the Bloor-Danforth Subway we know today was built instead.

A variation of the line appeared again in 1982, this time as a U-shaped line between Dundas West and Donlands stations via Union Station. This alignment was ultimately adopted as part of 1985's Network 2011 plan, from which the only substantial piece of infrastructure to actually be built was half of the Sheppard Subway.

Relief Line Recommended Route and Stations, image courtesy of the City of Toronto

The current incarnation initially appeared in Metrolinx's 2008 The Big Move, albeit under the 25-year planning horizon. In 2012, the project was bumped up and became one of the projects listed in the Next Wave of Metrolinx projects. In June 2016 the project was awarded $150 million for planning and design, marking the first significant investment in the project since the streetcar platform at Lower Queen was built over a half century before. Planning and design work is on-going, but the line won't be open to passengers until at least 2028.

On New Years Day, New Yorkers finally got to ride their subway line that was a century in the making. If the current timeline holds, Torontonians will need to wait almost another generation to ride theirs.