Template:Main Page/Historic byways/December/21

• Dec. 21, 1979 – Construction is completed on the Governor Edwin C. Johnson bore for eastbound Interstate 70 over the Continental Divide in Colorado
• Dec. 21, 1993 – The Delaware Route 1 toll road opens between Dover Air Force Base and Smyrna
• Dec. 22, 1989 – The recently completed Interstate 355, also known as the North–South Tollway, is dedicated by Governor James R. Thompson and U.S. Secretary of Transportation Samuel K. Skinner between Bolingbrook and Itasca, Illinois.
• Dec. 23, 1964 – Construction on the last segment of the Brooklyn–Queens Expressway, also known as Interstate 278, is completed in New York City.
• Dec. 24, 1959 – The newly constructed extension of Ontario Highway 401 between Barrie to Coldwater, is opened to traffic as a super two.
• Dec. 25, 1998 – A ruling by the Montana Supreme Court against speeding enforcement tactics used by the Montana Highway Patrol brings an end to the lack of numbered speed limits on Montana's state highways (pictured).
• Dec. 26, 1980 – Severe flooding of the Stillaguamish River leads to the closure of Washington State Route 530 to traffic between Stanwood and Silvana.
• Dec. 27, 1950 – Construction begins on the first section of Arizona State Route 84A (now Interstate 10) in Tucson, with the intended purpose of redirecting truck traffic away from the city's core.
• Dec. 28, 1955 – The Pennsylvania Turnpike Northeast Extension opens between US 22 near Allentown and a temporary interchange in Emerald
• Dec. 28, 1961 – The Woodrow Wilson Bridge is opened to traffic across the Potomac River between Alexandria, Virginia and Oxon Hill, Maryland in the Washington, D.C. metropolitan area.
• Dec. 29, 1955 – A marker is installed on Utah State Route 187 (now State Route 287), identifying the route as state's shortest designated highway.
• Dec. 30, 1940 – The remainder of the Arroyo Seco Parkway being constructed in Los Angeles, California between Avenue 40 and Avenue 22, is completed and opened to traffic, in time for the Rose Bowl and Tournament of Roses Parade the next day.
• Dec. 31, 1985 – The Connecticut Turnpike is officially renamed the Governor John Davis Lodge Turnpike after the recently deceased former state governor.