St. Augustine's Narrow Street

I hadn't heard of St. Augustine's "Narrowest Street in the U.S." until I came across this vintage postcard in an antique store. The back of the card reads:

 "TREASURY STREET, ST. AUGUSTINE, FLA.

NARROWEST IN U.S., 6 FEET 1 INCH.

In a town of many claims and exaggerations, (Fountain of Youth, Oldest House, Oldest School House, Oldest Store, etc.), I'm not sure if this one is true. In the second postcard it looks much wider, but the boast is still made. To test the width, I enlisted the help of a couple volunteers. You can see the results for yourself.