The data behind the story
The Houston Chronicle compiled the location and relevant information on 601,187 fatal roadway incidents in the U.S. from 2001 through 2016, using data from the National Highway Traffic Safety Administration. The federal database collects information determined at crash scenes, detailed by law enforcement.
The Chronicle plotted crashes on a map based on the location specified by the crash report, either by latitude and longitude or corresponding intersection. If no specific location was listed on the report, the accident was placed in the county in which it occurred for counting purposes.
We derived totals by counting crashes within the boundaries of the 12 largest metropolitan areas by population as of 2017, as determined by the Census Bureau. In Houston, the metropolitan statistical area is nine counties: Austin, Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery and Waller.
Population totals for 2001 through 2010 were derived using the 2000 and 2010 Census numbers and annual updates by the Texas State Demographer. From 2010 onward, populations were adjusted using Census Bureau estimates and the American Community Survey.
The Chronicle collected roadway fatalities and divided them into 12 categories, as identified by federal highway safety administrators: total fatalities; pedestrian fatalities; bicyclist fatalities; fatalities where speed was cited as a primary factor; fatalities on the national highway system; DUI-related fatalities; drug-related fatalities; fatalities involving multiple deaths; fatalities involving heavy trucks; fatalities at roadway intersections; fatalities where traffic congestion was cited as a factor; and fatalities related to road rage incidents or police chases.
We then compared the largest metro areas to each other in terms of deaths per capita based on population for that year as well as vehicle miles traveled, then ranked across each of the categories. Each of the individual rankings were considered and totaled, leading to an overall rank across all the criteria. Houston was the worst-ranked metro area by population, followed by Dallas and Phoenix. For miles of travel, Houston again topped the list, followed by Phoenix, then Dallas.