Today we released a new report describing the level and change of accessibility across the 51 metropolitan areas in the United States: Access Across America. The website includes an interactive map, the report can be downloaded directly here.

Executive Summary
Accessibility is the ease of reaching valued destinations. It can be measured across different times of day (accessibility in the morning rush might be lower than the less-congested midday period). It can be measured for each mode (accessibility by walking is usually lower than accessibility by transit, which is usually lower than accessibility by car). There are a variety of ways to define accessibility, but the number of destinations reachable within a given travel time is the most comprehensible and transparent as well as the most directly comparable across cities. This report focuses on accessibility to jobs by car. Jobs are the most significant non-home destination, but it is also possible to measure accessibility to other types of destinations. The automobile remains the most widely used mode for commuting trips in the United States.
This study estimates the accessibility in the 51 largest metropolitan areas in the United States for 2010, and compares results with 2000 and 1990.
Rankings are determined by a weighted average of accessibility, giving a higher weight to closer jobs. Jobs reachable within ten minutes are weighted most heavily, and jobs are given decreasing weight as travel time increases up to 60 minutes. Based on this measure, the ten metro areas that provide the greatest average accessibility to jobs are Los Angeles, San Francisco, New York, Chicago, Minneapolis, San Jose, Washington, Dallas, Boston, and Houston.
Job accessibility has changed over time. In the past two decades, Las Vegas, Jacksonville, Austin, Orlando and Phoenix have seen the largest percentage gains in job accessibility while Cleveland, Detroit, Honolulu and Los Angeles have seen the largest percentage drops.
Key findings

1. In 2010, the average American living in the top-51 metro areas could reach slightly fewer jobs by automobile than in 1990, but more jobs than in 2000.
2. Automobile speeds were faster in 2010 than in 2000 (and about where they were in 1990).
3. Overall job losses in these 51 areas have limited accessibility gains associated with faster networks.
4. The average American city is slightly more circuitous in 2010 than in 1990 because roads in newer areas (suburban growth) are not as well connected as those in older areas of the metropolitan region.
5. The overall most accessible metropolitan areas in 2010 were (in order): Los Angeles, San Francisco, New York, Chicago, Minneapolis, San Jose, Washington, Boston, Dallas, and Houston.
6. There have been significant changes among accessibility leaders since 1990, when New York, Philadelphia, Chicago, Miami, Los Angeles, Boston, Cleveland, Detroit, Washington, and Dallas made up the top 10.
7. People living in many smaller metropolitan areas can reach as many jobs by car as people living in much larger areas within both the 10- and 20-minute time frames. For instance New Orleans, Salt Lake City, and Jacksonville are all among the top 10 for number of jobs that can be reached within 10 minutes. Jacksonville, Milwaukee, and Las Vegas are among the top 10 for number of jobs that can be reached within 20 minutes.

There are two ways for cities to improve accessibility—by making transportation faster and more direct or increasing the density of activities, such as locating jobs closer together and closer to workers. While neither of these things can easily be shifted overnight, they can make a significant impact over the long term.