The Narrows upstream from The Bridge to Nowhere - East Fork Trail above Azusa, CA travels up the East Fork of the San Gabriel River. The 10 mile trail is considered moderate with 1200 foot of gain, it has parallel trails and many dead ends. Expect numerous water crossings and should not be done if rain is expected. Beyond the bridge the river area enters what is called the Narrows where there are pools for summer swimming.
The history here is the bridge was started in 1929 up the East Fork of the San Gabriel River, in 1935 they began the work on the bridge. The bridge was completed in November 1936. March 1-2, 1938 fourteen inches of rain fell into the San Gabriel Mountains and a 50 foot flow washed out the road and other bridges except this 120 foot bridge, which is higher than everything else.