Largest Transit Systems in North America

Public transit is the circulatory system of big cities. It gets millions of people to work and school, shapes where housing and offices get built, and quietly determines how congested the roads feel at rush hour. In North America, “largest” transit systems aren’t just big in scale—they’re complex machines made of subway tunnels, bus lanes, commuter rail tracks, and intercity connections that have grown and evolved for more than a century.

This article takes a deep look at the largest transit systems in North America: how we define “largest,” which cities dominate by different metrics, and how buses, subways, and regional rail networks knit together into vast mobility systems. Along the way you’ll see real ridership, network, and capacity data to ground the story in numbers, not just vibes.

1. How many people actually use transit in North America?

Before zooming into individual cities, it helps to get a sense of the overall scale.

In the pre-pandemic year of 2019, riders in the United States alone took about 9.9 billion trips on public transportation. Lockdowns and remote work crushed ridership in 2020, dropping usage by around 40%. By 2023, ridership had rebounded to about 7.1–7.2 billion trips, still roughly 25–30% below 2019 levels.

APTA’s most recent policy brief estimates that by 2024, riders in the U.S. took about 7.7 billion trips, and by spring 2025 national ridership had reached roughly 85% of pre-pandemic levels.

Canada and Mexico follow similar patterns: deep pandemic drops and partial recovery, but with big differences between cities. Dense, transit-oriented places like New York City, Mexico City, Toronto, Montreal and Vancouver still see very high per-capita transit use, especially on their rail networks.

So when we talk about the “largest” systems, we’re talking about networks that handle hundreds of millions to billions of passenger trips per year, even after a once-in-a-century shock.

2. What does “largest” actually mean?

There are several ways to define the size of a transit system, and they don’t always point to the same winners:

• Annual ridership (unlinked trips) – How many times riders board vehicles (each transfer counts as another trip). This is the most common metric in U.S./Canadian statistics.

• System length – Total miles or kilometers of track or busway.

• Number of stations or stops – A proxy for geographic coverage and accessibility.

• Service supplied – Vehicle-kilometers or vehicle-hours of service.

• Agency scale – Total ridership across all modes a transit agency runs (subway, light rail, bus, commuter rail, BRT, etc.).

In this article:

• Section 3–4 focus on heavy-rail / metro systems (the subway-style networks).

• Section 5 looks at multi-modal transit agencies—the entities that run everything from subway cars to local buses.

• Section 6–7 highlight bus and commuter rail as critical pieces of the “largest systems” picture.

3. The kings of the subway world: North America’s busiest metro systems

By heavy-rail (metro/subway) ridership, North America has a clear hierarchy. The table below uses the latest compiled figures for 2023 annual ridership from the List of North American rapid transit systems by ridership, which in turn relies on APTA data for the U.S. and Canada and national statistics for Mexico.

Table 1 – Largest North American heavy-rail systems by annual ridership (2023)

Data source: compiled from APTA and national statistics via the “List of North American rapid transit systems by ridership” (2023 figures; lengths and station counts from the same source and individual system articles).

A few patterns jump out:

• New York and Mexico City are in a league of their own. Each carries more than a billion rides per year, dwarfing other systems in the region.

• Canada punches above its weight. Toronto, Montreal, and Vancouver all have high ridership relative to their metro-area populations, reflecting land-use patterns and transit-oriented planning.

• Historic U.S. metros like Chicago and Washington remain core players, though their ridership, like others, took a hit during COVID and is still recovering.

Let’s zoom into a few of these.

4. Deep dives: the biggest metro networks

4.1 New York City: the archetypal mega-system

By almost any metric, the New York City Subway is North America’s transit leviathan:

• Annual ridership: Roughly 2.04 billion trips in 2023, making it the busiest rapid transit system in the Western Hemisphere.

• 2019 (pre-COVID) ridership: About 1.698 billion trips.

• Network size: 472 stations and more than 665 miles of track, with about 399 km of route length used for the rapid-transit ranking.

The subway is only part of the picture. The MTA also operates one of the world’s largest bus fleets:

• Bus ridership: ~678 million annual bus trips in 2019 for New York City Transit buses.

• Fleet & coverage: Almost 6,000 buses running 234 local routes, 20 Select Bus Service (BRT-like) routes, and 73 express routes across the five boroughs.

Put together, the subway plus bus network delivered around 2.4 billion trips in 2019, and even in 2023–24 remains the backbone of mobility in the metropolitan area.

New York’s secret sauce is not just size, but network density:

• Multi-branch services like the A/C/E and 4/5/6 saturate Manhattan’s core.

• There are multiple cross-Manhattan links (e.g., 42nd Street, 14th Street), enabling strong transfer patterns.

• Outer boroughs rely on buses feeding the subway, with huge transfer volumes at stations like Fordham Road, Jamaica Center, and St. George.

The result is a true 24/7 network where a large share of trips, especially in Manhattan, can be done entirely on transit.

4.2 Mexico City: high ridership and high density

The Mexico City Metro is the second-busiest rapid transit system in North America, with about 1.115 billion trips in 2023 and a network of ~226.5 km and 195 stations.

What’s striking about Mexico City:

• It achieves enormous ridership with lower fares and relatively shorter distances than New York.

• Many riders depend on it because car ownership is lower and the city’s traffic congestion is intense.

But the metro is only one layer in a multi-modal web that includes:

• Metrobús BRT corridors: Seven main BRT lines carrying about 1.24 million passengers per day along roughly 140 km of busways.

• Extensive microbus and collectivo networks and regional buses feeding into Metro and BRT stations.

Combined, this makes Mexico City one of the most transit-dependent big cities in the Western Hemisphere.

4.3 Toronto and Montreal: Canadian metro powerhouses

The Toronto subway and Montreal Metro sit almost neck-and-neck in annual metro ridership (around 0.33 billion trips each in 2023), despite different designs and histories.

Toronto (TTC subway)

• Network: About 80 km of route with 80+ stations as of mid-2020s expansions; 76.9 km and 70 stations in the 2023 ranking.

• Daily demand (pre-COVID): Roughly 2.07 million rail trips (including transfers) on an average business day in 2019 across subway, LRT, and streetcar.

Toronto’s network is classic “radial” transit:

• Line 1 (Yonge–University) forms a U-shaped backbone through downtown.

• Line 2 (Bloor–Danforth) runs east–west across the city.

• Line 4 (Sheppard) and the under-construction Ontario Line add more cross-town capacity. The Ontario Line alone is a new 15.6 km subway, tunneling and running elevated from Exhibition Place to Don Mills.

Montreal (STM Metro)

• Network: 69.2 km of entirely underground, rubber-tired metro with 68 stations; it connects central Montreal to Laval and Longueuil.

• STM ridership: About 283.5 million boardings in 2019 across its network, with the metro alone handling roughly a million weekday trips.

Montreal is also layering in the Réseau express métropolitain (REM), an automated light-metro system that will eventually total 67 km and 26 stations across the region.

Together, subway/metro lines plus bus networks give Toronto and Montreal extremely high per-capita transit usage, even compared with some U.S. cities with larger metro-area populations.

4.4 Washington, Vancouver, Monterrey, Chicago: regional workhorses

Washington Metro (WMATA)

• Ridership: About 0.167 billion trips in 2023, making it the second-busiest U.S. heavy-rail system after New York.

• Network: ~129 miles (208 km) of route, 98 stations, serving D.C. plus Maryland and Virginia suburbs.

WMATA’s rail ridership hit about 182 million trips in 2019, then plunged during COVID and has been steadily climbing back as more office workers return and service frequency improves.

Vancouver SkyTrain

• An automated driverless rail network with ~79.6 km of route and 53 stations, carrying around 149 million trips in 2023.

• It has some of the highest ridership per route-kilometer in North America and is tightly integrated with Vancouver’s bus and commuter rail services to form a seamless regional system.

Metrorrey (Monterrey) and the Chicago “L” round out the top eight, underscoring that big, high-use metros aren’t limited to the absolute biggest cities. Chicago’s system remains large in route-length (over 165 km) and station count, even though ridership has seen long-term erosion from competition with cars and ride-hailing.

5. The giants behind the scenes: largest multi-modal transit agencies

Focusing only on subways can be misleading, because the largest transit “systems” are often agencies that run multiple modes: heavy rail, light rail, commuter rail, and big bus fleets.

The American Public Transportation Association’s 2019 Fact Book includes a ranking of the 50 largest U.S. transit agencies by unlinked passenger trips (2017 data).

Table 2 – Largest U.S. transit agencies by total unlinked trips (2017)

Values converted from thousands of unlinked passenger trips reported in the 2019 APTA Fact Book (2017 NTD data).

A few observations:

• NYCT is absolutely dominant: over 3.4 billion unlinked trips, nearly an order of magnitude above the next largest U.S. agency.

• Agencies like CTA, LA Metro, MBTA, and WMATA operate sizable rail systems and massive bus fleets. Their total system size comes as much from buses and commuter rail as from the subway proper.

• NJ Transit is interesting: its total ridership is dominated by commuter rail and regional buses, highlighting the role of longer-distance commuting into New York and Philadelphia.

If we added Canada and Mexico, agencies like TTC (Toronto), STM (Montreal), TransLink (Vancouver) and Sistema de Transporte Colectivo / Metrobús (Mexico City) would clearly join the list of mega-agencies.

6. Buses: the unsung workhorses

Buses rarely get the press that new rail lines do, but they carry enormous shares of trips even in rail-rich cities.

6.1 New York City buses

As noted earlier, New York City Transit buses handled around 678 million trips in 2019, on top of nearly 1.7 billion subway trips.

Useful stats:

• ~2.2 million bus boardings per weekday (2019).

• 5,927 buses, all wheelchair-accessible.

• 234 local routes + 20 “Select Bus Service” routes that add bus-only lanes, off-board fare payment, and all-door boarding.

New York’s total transit “system” is thus a subway-bus hybrid, with huge bus corridors in outer boroughs feeding the subway grid.

6.2 LA Metro: a bus-heavy giant with expanding rail

Los Angeles is famous for cars, but LA Metro runs one of the continent’s largest bus fleets plus a growing rail system:

• LA Metro’s combined bus and rail network delivers over 400 million unlinked trips per year (pre-COVID), making it the third-largest U.S. transit agency by ridership.

• Historically, most of that ridership has been on local and rapid buses, with rail lines growing but still forming a smaller share of trips.

The A Line, part of Metro Rail, is now the longest modern light-rail line in the world, at about 57–58 miles (92–93 km) after its 2025 extension to Pomona, with 40+ stations.

That extension is emblematic of LA’s strategy: use long, continuous rail lines and BRT corridors to connect far-flung suburbs and activity centers in an extremely dispersed metro area.

6.3 Mexico City’s Metrobús and beyond

Mexico City’s Metrobús network is one of the world’s most intensively used BRT systems:

• 1.24 million passengers per day across seven corridors and about 140 km of dedicated busways.

Metrobús acts both as:

• A parallel backbone along some of the city’s major avenues.

• A feeder system connecting outlying neighborhoods to metro stations, similar to how big bus systems feed subways in New York or Toronto.

6.4 Surface transit in Canada

In Toronto, buses and streetcars are essential:

• 2019 TTC statistics show over 3.3 million total daily trips (including subway, streetcar, bus), with about 1.7 million revenue passengers paying fares on an average business day.

• Many of those trips occur on surface routes—particularly the downtown streetcar network and key bus corridors feeding subway stations.

Montreal’s STM also operates over 220 bus routes and 23 night routes, giving the metro a wide catchment area.

7. Commuter and regional rail: stretching the reach of big-city systems

Commuter rail lines often get left out of “largest system” lists because their ridership is typically smaller than subways. But in North America’s biggest metro regions, they are critical parts of the total network.

7.1 The New York region: LIRR, Metro-North, NJ Transit

The New York region has several major commuter rail systems:

• MTA Long Island Rail Road (LIRR) and Metro-North Railroad are among the largest commuter railroads in the U.S.

• NJ Transit operates extensive commuter rail corridors west of Manhattan and buses that feed rail hubs.

APTA’s rankings show MTA LIRR alone logging over 100 million unlinked trips in 2017, while NJ Transit records hundreds of millions of trips across rail and bus operations.

These lines:

• Extend the reach of transit to suburban and exurban communities.

• Allow New York’s core to support huge job densities without being overwhelmed by cars.

• Are now being bolstered by mega-projects like the East Side Access / Grand Central Madison concourse and capacity expansions in New Jersey and the Hudson River tunnels.

7.2 Toronto and the GO Transit network

In the Greater Toronto Area, GO Transit (operated by Metrolinx) runs regional rail and bus services that connect downtown Toronto with cities like Hamilton, Kitchener, Oshawa, and Barrie.

While GO’s total ridership is lower than the TTC’s, it:

• Carries large volumes of peak-hour commuters.

• Has been undergoing a long-term GO Expansion program to electrify and increase frequencies, nudging service closer to a European-style regional metro.

7.3 SF Bay Area: BART and friends

In the San Francisco Bay Area, BART is technically a regional metro, but functionally behaves like commuter rail on long stretches—its system spans ~211 km of track and 48 stations, with about 51 million trips in 2023.

Add in:

• Caltrain (commuter rail).

• Local bus systems and light rail (Muni, VTA, AC Transit).

Together they form a polycentric transit region where no single agency tells the whole story.

8. How these systems shape their cities

Large transit systems don’t just move people; they shape urban form.

8.1 Land use and density

• In New York, dense subway coverage has allowed extreme job concentrations in Manhattan and increasingly in Brooklyn and Queens, with high transit mode shares for commuters.

• Mexico City’s Metro and BRT support dense apartment neighborhoods and commercial corridors along their alignments, though informal development and congestion remain challenges.

• Toronto, Montreal, and Vancouver have embraced transit-oriented development (TOD) around subway and SkyTrain stations, driving higher densities and condo construction in station areas.

8.2 Equity and access

For many riders, especially in lower-income neighborhoods:

• Buses and subways are essential services, not lifestyle choices.

• Service reductions or fare hikes can sharply reduce access to jobs and education.

Studies after the pandemic show that ridership fell fastest among higher-income commuters with remote work options, while essential workers kept using transit, particularly buses and local rail. Agencies had to adjust service patterns to reflect this new reality.

8.3 Environmental and congestion impacts

Switching from car to transit:

• Can cut CO₂ emissions by up to 73% for individual trips when riders use subways instead of cars, according to long-standing FTA analyses.

• Helps reduce congestion, especially in cities where transit captures a meaningful share of peak-hour trips (e.g., Manhattan, central Montreal, downtown Toronto).

9. Challenges and what’s next for North America’s largest transit systems

9.1 Pandemic recovery and shifting travel patterns

Transit agencies across North America are wrestling with:

• Ridership recovery that’s uneven by mode – rail commuting into CBDs is still below 2019 levels, while bus ridership and off-peak/leisure trips are recovering more strongly.

• Fiscal cliffs – emergency federal support is winding down, forcing agencies to weigh service cuts, fare hikes, or new funding streams.

• New travel patterns – more mid-day and weekend ridership, fewer five-day-a-week commuters.

Large systems like MTA, CTA, LA Metro and others are experimenting with:

• More all-day frequent service, not just rush-hour peaks.

• Better bus priority (bus lanes, TSP).

• Fare structures that reward frequent riders even if they only commute a few days per week.

9.2 Mega-projects and expansions

Some major expansions will reshape the map in the 2020s:

• Ontario Line (Toronto): A new 15.6 km automated subway that will relieve the overloaded Line 1 and create new cross-town connections.

• REM (Montreal): A 67 km, 26-station automated light-metro network connecting downtown Montreal with suburbs and the airport.

• LA Metro rail expansions: Extensions of the A Line and other rail projects continue to expand the footprint of rail in a region long dominated by freeways.

These mega-projects aim to:

• Increase capacity on the busiest corridors.

• Extend frequent, high-quality transit into growing suburbs.

• Support climate goals by shifting more trips from cars to transit.

9.3 Maintenance and state of good repair

Large, aging systems—most notably New York, Chicago, Boston, and parts of Mexico City’s Metro—face massive maintenance backlogs:

• Old tunnels, signals, and rolling stock require ongoing investment to avoid failures and derailments.

• High-profile incidents (like Washington Metro’s 7000-series derailment and subsequent fleet pullback) have highlighted the importance of safety and state of good repair.

For big agencies, the hardest challenge is often not building something new, but keeping the existing system reliable while still expanding.

10. Putting it together: what “largest” really tells us

Looking across North America’s largest transit systems, a few themes emerge:

1. Sheer scale matters: Systems like New York City and Mexico City move billions of riders annually; even modest percentage changes in their ridership represent hundreds of millions of trips.

2. Bus networks are crucial: Subway maps get framed on walls, but in almost every big city the bus system carries a huge share of trips and stitches together areas the rail network doesn’t reach.

3. Regional connectivity extends urban transit: Commuter rail and regional buses in places like the New York and Toronto regions greatly expand the reach of core transit networks.

4. Recovery and reinvention are ongoing: Post-COVID ridership is rising but still below 2019 levels in many places, pushing agencies to experiment with new service patterns, fare policies, and capital plans.

In short, the largest transit systems in North America are less a set of individual subway lines and more whole ecosystems of mobility—multi-layered networks of subways, buses, trams, BRT corridors, and commuter rail that together move tens of millions of people every day.