Professor Schweitzer supplied her students with a spreadsheet of the number of jobs reachable via transit and auto in 10-minute intervals, which became my primary source for this visualization. I depict the extreme differences in job opportunity access by transit vs. car with string, inspired by the radii of travel paths that a worker could take from her home to her job.
I chose 30 minutes as my selected time interval, based on the average commute time in the U.S. I selected four cities with 1+ million jobs accessible in a 30-minute car trip that also had the smallest percentages of those jobs accessible via transit. I treated the jobs reachable via auto in 30 minutes as the greatest number of jobs reachable in 30 minutes and inclusive of the jobs reachable by transit.
With the highest percentage of jobs accessible via transit (8%), New York (green) is included for purposes of comparison with the 1+ million-job cities with the lowest job access via transit. By their respective auto and transit 30-minute values, these cities include:
1. Detroit (purple) - 0.6% of ~988,000 jobs accessible via transit
2. Dallas (blue) - 0.75% of ~1.35 million jobs accessible via transit
3. Phoenix (yellow/orange) - 1% of ~1.01 million jobs accessible via transit
4. Houston (pink) - 1.32% of ~1.15 million jobs accessible via transit
*Source: I obtained this data from Professor Lisa Schweitzer's course materials. She told me that the data came from Dr. David Levinson's research on job access via cars and transit at the University of Minnesota's Center for Transportation Studies.