This photo from 1911 shows the confluence of eras as progress trundles down 11th Avenue, New York City.

The commercial boulevard running along Manhattan's West side was a battleground for movement, pitting pedestrians, horses and carriages against the perennial trains of the New York Central Railroad. Simple physics determined the victor of the collisions, and 11th Avenue became commonly known as "Death Avenue".

To remedy the situation, men on horseback would ride ahead of the trains, waving flags and warning travelers of the oncoming locomotives. These men were called the West Side Cowboys.