Cause of the collapse Business St. Paul, Minn. · Jan 16, 2008 Pieces of the puzzle MPR Photo/Jim Bickal As part of MPR's coverage of the I-35W bridge, Midday features a special report on the National Transportation Safety Board's investigation of the cause of the collapse. Stay Informed The news on your schedule from MPR News Update Email Address* Zip Code MPR News Update AM Edition MPR News Update PM Edition See our Privacy Policy. Must be age 13.