I was wondering the same thing! Wikipedia says: [1]
> In the United States, the first documented use of a painted center line was in 1911... According to the state of Michigan, the idea of using a painted center line was conceived in 1911 by Edward N. Hine...
> In the UK, the first "white line" road markings appeared on a number of dangerous bends on the London-Folkeston road at Ashford, Kent, in 1914, and during the 1920s the rise of painted lines on UK roads grew dramatically. In 1926 official guidelines were issued by the Ministry of Transport that defined where and how white lines on roads should be used.
