http://motherboard.vice.com/blog/in-1897-a-bicycle-superhighway-was-the-future-of-california-transit
http://www.fhwa.dot.gov/infrastructure/the_great_cycle_way_.cfm
This was a nine-mile*, four-lane freeway for bicycles, leading from Pasadena toward downtown LA. Wide enough for four riders abreast, and there was talk of widening it. Built of wood, elevated, and grade-separated from streets and railroads. Toll was 10 cents one-way, and 15 cents round trip.
Unfortunately, it looks like all traces are gone; and part of the corridor is now the Arroyo Seco Parkway.
This was near the apex of the Good Roads movement, sparked by cyclists, within a few decades for the benefit of the automobile.
* only 1.25 miles of this was constructed