Route 198 was commissioned in 1932, running along the current route of Route 171 from former Route 15 (now I-84) in Union to former Route 91 (now Route 171) in Woodstock.
Connecticut | Hartford, Connecticut | New Haven, Connecticut | University of Connecticut | U.S. Route 66 | Greenwich, Connecticut | U.S. Route 1 | Bridgeport, Connecticut | Stamford, Connecticut | Norwalk, Connecticut | New London, Connecticut | U.S. Route 6 | U.S. Route 101 | Connecticut River | Route 66 | U.S. Route 30 | New Jersey Route 4 | Mystic, Connecticut | European route E65 | U.S. Route 40 | Norwich, Connecticut | California State Route 1 | U.S. Route 1 in Maine | Pennsylvania Route 309 | Middletown, Connecticut | European route E18 | U.S. Route 23 | European route E4 | Wethersfield, Connecticut | Waterbury, Connecticut |