A high-tech study that meticulously studied the conditions of U.S. roads found that Michigan has the worst roadways in the nation.

Overall, American roads received a “D” on the report card but Michigan had the distinction of finishing last among the 50 states.

The study was conducted by Lyft Level 5, a company founded by ex-Tesla engineers that aims to build high definition maps for self-driving cars, according to WWTV/WWUP-TV in northern Michigan.

Level 5’s HD maps were created by analyzing more than 15 million photographs captured by iPhone dash cams. The photos showed intricate details of each road studied in four categories: Fading road markings, cracking pavement, potholes and surface flatness.

HD maps are a key component to advancing self-driving technology, providing far more detail for autonomous cars than basic web services which offer turn by turn directions to drivers of regular vehicles.

The study found that Michigan’s road system was 50th, followed by Iowa, Indiana, Ohio and Kansas for the worst road conditions in the U.S.

In contrast, Florida had the best roads, with Hawaii and Washington State not far behind.