North of Thirsk, the A19 takes over from the A168 as the link from the A1 to Teesside and becomes a fast dual carriageway with mostly grade separated interchanges. The five-mile £4.4 million Thirsk bypass was opened on 5 September 1972 by Robin Turton, Baron Tranmire, the local MP (from 1929), with a flypast by four Royal Air Force Vickers Varsity aircraft - RAF Topcliffe is to the south-west of Thirsk. It passes North Kilvington, and the £0.3 million South of Knayton (at Swan Lane) to north of Thirsk bypass section opened in the early 1970s. It climbs slightly past the junction at Knayton near Borrowby and skirting the western edge of the North York Moors, meeting the A684 (for Northallerton) at Clack Lane End after passing through Leake and by the "Haynes Arms". The Borrowby diversion opened in the late 1960s. The £1.1 million south of Clack Lane End to north end of Borrowby diversion opened in the early 1970s. The Cleveland Tontine to Clack Lane End improvement opened in the early 1970s. It drops towards the Cleveland Tontine at the junction with the A172 (for Stokesley and Guisborough). later, it passes the BP "Exelby Services" on both sides of the road. Eventually after passing the Crathorne/Yarm exit the road passes over the Leven viaduct towards Teesside. From the Crathorne bypass, the road leaves the old route to the east, with the old route now being the A67 then the A135 through Stockton. About from the Parkway Turn (A174) in Middlesbrough the road is raised slightly, overlooking Thornaby industrial estate and one of Europe's biggest housing estates known as Ingleby Barwick, giving clues that Teesside is imminent.