In 1927, the Holland Tunnel opened for vehicular traffic as the first twin tube subaqueous vehicular tunnel in the U.S. It joined Jersey City, N.J. and New York City, N.Y. The day before, after an opening ceremony, in the next hour 20,000 people walked the 9,250 feet length of the tunnel from shore to shore, of which 5,480-ft runs under the river. Named after its engineer, Clifford Holland, the tunnel carries 1,900 vehicles per hour. The air in the tubes is changed 42 times an hour, at the rate of 3,761,000 cubic feet per minute. The first subaqueous highway single tube tunnel in the U.S. was the 1,520-ft long Washington Street Tunnel beneath the Chicago River in Chicago, Illinois, which was first authorized 17 Jul 1866, though it did not carry automobile traffic until 1911.