Decommissioned highway

Decommissioning can include the complete or partial demolition or abandonment of an old highway structure because the old roadway has lost its utility, but such is not always the norm.

Where the old highway has continuing value, it likely remains as a local road offering access to properties denied access to the new road or for use by slow vehicles such as farm equipment and horse-drawn vehicles denied use of the newer highway.

Decommissioning can also include the removal of one or more of the multiple designations of a single segment of highway.

Some highways may be partly decommissioned, such as two segments of M-21 in Michigan from Holland to Grand Rapids as Interstate 196 and between Flint and the Canadian border at the Blue Water Bridge as Interstate 69 (I-69) supplanted much of it and M-21 remained in existence between Grand Rapids and Flint.

[2] US 33 in Lancaster, Ohio, was signed as US 33 Business following relocation of US 33 and construction to Interstate Highway standards.

US 66 in the midwestern and southwestern United States is a prime example of such efforts; "Historic Route US 66" markers, completely unofficial, designate most of the old surface road, some of which has literary significance (as in John Steinbeck's novel The Grapes of Wrath).

Two of the lanes are provincially maintained for automobile traffic by the St. Lawrence Parks Commission but the other pair have been replaced with footpaths and a bicycle trail.

In the Republic of Ireland, National Primary Routes are often realigned after the construction of new motorway sections, dual carriageways or bypasses.

Pennsylvania Route 611 was known as US 611 , but was downgraded to a state route as it was entirely in Pennsylvania . This old US 611 sign, along the ramp from Cheltenham Avenue to PA 611 on the border of Philadelphia and Cheltenham , was still present in 2014, but has been removed as of 2022.