This archive presents the results of archaeological investigations carried out by Northern Archaeological Associates in conjunction with Highways England's 2013-2017 scheme to upgrade 19km of the A1 trunk road to motorway status between Leeming and Barton in North Yorkshire. The digital archive comprises scheme-wide data produced as part of the archaeological project, including supplementary appendices to five monographs. It also includes published archaeological results from a previous A1 upgrade scheme between Dishforth and Leeming during 2009-2010. While the A1 scheme passed through a known area of archaeological significance, remains ranging from the Mesolithic through to the Anglo-Saxon period exceeded all expectations. Amongst the sites investigated were: an Early Mesolithic camp at Little Holtby, near Leeming; a Bronze Age funerary site at Bowbridge Lane; a Roman cemetery and roadside settlement at Bainesse; parts of the Roman town at Cataractonium; a Roman roadside settlement at Scurragh House, and a Late Iron Age to Early Roman settlement at Scotch Corner.