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Mapped: How public transit changes your job prospects

Washington, D.C. <a href="">The Accessibility Observatory</a> , the University of Minnesota Center for Transportation Studies
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Public transit dramatically changes the shape of a city for people who live near (and rely on) it. A job that may be five miles away feels much closer if it's on the other end of a subway line. A supermarket in the next neighborhood over may feel remote if there's no bus to get to it.

The amenities in a city, for many people, are only as accessible as its transit system. And the better that transit system — with broad coverage, short waits, easy transfers — the more accessible the city is. This is true in all kinds of ways, for all kinds of destinations, but it's particularly relevant for regional economies — and even social mobility — when it comes to talking about jobs.

In New York City, for example, tens of thousands of jobs are readily accessible within a quick transit ride for residents living across broad stretches of town. In Cincinnati, public transit more often fails residents in this fundamental role: connecting them to work.

In a new analysis from the Accessibility Observatory, a research group at the University of Minnesota, New York City offers in fact the best transit access to jobs of any big city in the country. To understand how the researchers, headed by Andrew Owen and David Levinson, determined this, consider the below map. It shows every Census block in the New York metro region, each one colored by the number of jobs that are reachable, on average, within a 30-minute commute by foot and transit leaving between 7 and 9 a.m.

1. New York

For about a year now, the Accessibility Observatory has been doing this painstaking work, trying to calculate job access through transit from thousands of locations in dozens of cities, starting from every minute of the day. Their analysis draws on public transit schedules, Census data on the location of jobs, and route-planning apps capable of calculating the shortest path between any two points in a city.

The calculation takes into account the amount of time it may take to walk to the bus or train stop, to wait for it to arrive, to transfer between lines mid-trip, and to walk from the last stop to your destination. For every Census block in the city, Owen and Levinson have drawn a shortest-path tree to every job within a 30-minute radius, starting at 7 a.m. Then at 7:01. Then 7:02 (your circle of available jobs changes a lot if you've just missed the bus, or if you've arrived just in time for the next one). The above map of New York reflects the number of jobs accessible across the two-hour morning rush hour, averaged across every minute.

This is just one way of slicing the data. With their analysis, the Accessibility Observatory can do the same with a 45-mintue commute, or a 60-minute one, or starting mid-afternoon or late at night. Their rankings of 46 of the 50 largest metros in the U.S. (excluding Jacksonville, Memphis, Oklahoma City, and Richmond, which don't easily provide transit schedule data) consider different commute lengths and windows of time, weighting nearby jobs more than far-away ones.

This exercise is tremendously intricate, but also limited. It doesn't take into account the difference between a $100,000-a-year managerial job and a minimum-wage fast food gig, although future analyses could do that. It's also true that each of us needs only one (maybe two) jobs, so knowing that there are 200,000 of them within 30 minutes of your doorstep may not be personally relevant to you.

But, at a macro level, these pictures reveal which neighborhoods have the best job access, where residents have to make the longest commutes to find employment, and where your prospects for easy access to work will be the highest if you lose one job and need another. The differences that emerge between metros may also tell us something about why some cities seem to offer greater chances for economic mobility than others.

From a transit perspective, these maps can also illustrate how small changes in service — a few more buses at rush hour, more frequent connections in the subway — could dramatically alter access to jobs across town.

Below are maps for the rest of the report's top five metros. They also show employment accessible within a 30-minute commute, between 7-9 a.m. Bear in mind that the results say as much about the quality of transit as the location and quantity of jobs (No. 30 Atlanta, for instance, has a more extensive transit network than some other cities, but its jobs are also more highly decentralized).

2. San Francisco

3. Los Angeles

4. Washington

5. Chicago

For comparison, here are two cities ranked near the bottom of the list:

44. Virginia Beach

46. Birmingham