The site of the Amtrak 188 crash in May 2015 was at the curviest track stretch between Washington and New York, excluding station approaches, I found in this story for The Upshot at The New York Times. This story combines traditional human-sourced reporting with data analysis from spatial analysis of data from the U.S. Department of Transportation.

I open-sourced the Makefile I used to create the data for this story.