 Welwyn was noted for its congestion since the beginning of the 20th century, but in 1927 it got what is claimed to be the first by-pass in Britain.The A1 was upgraded to motorway standards north of Welwyn in the 1960s, and in 1973 the motorway was extended south past the village, by-passing the existing by-pass.Today the village is the point where the six-lane motorway merges into four lanes and is the site of extensive traffic jams in the evening peak.