route travels east into St. Thomas, becoming a two-laned expressway aptly named the St. Thomas Expressway. This expressway begins at Wellington Road (Elgin County Road 25/26) and travels through St. Thomas to Centennial Road, featuring a single interchange. However, the right-of-way is wide enough to accommodate any future upgrade to a divided expressway. At the eastern end, Highway 3 turns south onto Centennial Road and then east onto Talbot Line, following the historic Talbot Trail to east of Aylmer. This mostly straight and rural portion passes through several small villages before the Talbot Trail splits from it to follow Elgin/Norfolk County Road 38 through Straffordville. Highway 3 meanwhile curves northeast and passes through Tillsonburg, encountering Highway 19. It then curves east and travels parallel to the St. Thomas and Eastern Railway to Courtland, remerging with the Talbot Trail and snaking towards Delhi, now within Norfolk County. At Delhi, Highway 3 turns south for before returning to its eastward orientation. It continues through farmland to the town of Simcoe, where it meets Highway 24. From Simcoe to Canborough, the highway is nearly straight as an arrow, with an occasional jog to the northeast. It enters Haldimand County and intersects Highway 6 in Jarvis. At Cayuga it crosses the Grand River; until 2014, a five-span steel girder bridge crossed the river, but it has since been replaced by a concrete structure. At Canborough, the historic Talbot Trail ends and Highway 3 veers south to Dunnville, briefly travelling along the northern bank of the Grand River and gradually curving back eastward. East of Dunnville, the route follows Forks Road into Wainfleet and the Niagara Region. At Chambers Corners it turns south and passes through Wainfleet village, crossing the old Feeder Canal which once supplied the Welland Canal with water from the Grand River. Just north of Lake Erie, Highway 3 turns east and travels straight towards Port Colborne, passing just south of the Wainfleet Bog. At Townline Road, the boundary between Wainfleet and Port Colborne, the central section ends and the roadway continues as Niagara Regional Road 3 through the city, meeting the southern end of Highway 58. Portions of the central segment of Highway 3 through several towns are maintained under Connecting Link agreements, including within Aylmer, Delhi, Simcoe, Cayuga and Dunnville. The combined length of these segments is . Eastern segment The final and shortest section of Highway 3 begins at