The A172 is a major road in North Yorkshire, and the unitary authority of Middlesbrough, England. It runs from Ingleby Arncliffe to Middlesbrough. The road derives its adumbrated number from 1969 when a thoroughfare link connected South Teesside with the Lackenby Docks in Middlesbrough. Since further urban infrastructure development it has been extended into the North Yorkshire Moors, when it transforms into A174.