In California, Nevada, Florida and the District of Columbia, the future of transportation is now: All four states have made self-driving cars legal. Why?The trend is spreading. In this year's legislative sessions, nine more states debated self-driving car bills. While most of the bills died in committees, Michigan's bill is likely to pass by the end of the year with support from Republican Gov. Rick Snyder, a former tech titan who advocated for the new car technology.

Quote from Gov. Snyder: "(California, Nevada and Florida) are ahead of us, and aren't we the automotive capitol of the world?" Snyder said earlier this year. "So, I think we should be stepping it up here and make sure we are on the forefront of advances [in] vehicles and opportunity."

At the local level, self-driving cars will change the way cities think about zoning, parking and idling rules, and could eventually allow cities to develop small shuttle-like systems, which would drive predetermined routes and ferry people to and from popular destinations.

The bottom line is driver less cars means fewer accidents.