Lake McCoppin was a body of water filled in gradually during the 1800s, and was nearly completely gone by the 1870s. The last remaining patch of it stretched from Dolores Street to Mission Creek, between 17th Street and 19th Street. Lake McCoppin was the name in the mid to late 1800s for the remnants of a larger lake called Laguna de Mañana.

So, as you are bicycling down this stretch of urban landscape, consider that it's nice and flat because it was a lake bed!