Wikipedia:WikiProject U.S. Roads/Connecticut/List of 1920s numbers

The main source for this list is the 1926 maps at.

Routes 1-99

 * Route 1, NY to RI via New Haven, New London
 * Now U.S. Route 1
 * Route 2
 * Now U.S. Route 5
 * Route 3
 * Now Route 35, U.S. Route 7, U.S. Route 6
 * Route 4, NY to MA via Sharon, Salisbury
 * Now Route 343, Route 41
 * Route 8, Stratford to MA via Derby, Waterbury, Torrington, Winsted
 * Now Route 110, Route 8
 * Route 10, Saybrook to MA via Middletown, Hartford, Granby
 * Now Route 9, Route 99, Route 189, Route 10
 * Route 12
 * Now Route 32, Route 12
 * Route 17, MA to west of Westerly via Canaan, Winsted, Hartford, Colchester, Norwich
 * Now U.S. Route 7, U.S. Route 44, Route 2
 * Route 32
 * Now Route 12, Route 32, Route 19

Routes 101-199

 * Route 101, South Chaplin to RI
 * Now Route 198, US 44
 * Route 102, New London to Colchester
 * Now Route 85
 * Route 103, Central Village to RI
 * Now Route 14
 * Route 104, Middletown to Glastonbury
 * Now Route 17
 * Route 105, Thompsonville to Stafford Springs
 * Now Route 190
 * Route 106, Clinton to Higganum
 * Now Route 81
 * Route 107, Talcottville to West Ashford
 * Now Route 30 and Route 74
 * Route 108, South Manchester to MA
 * Now Tolland Turnpike and Route 83
 * Route 109, Bolton Notch to Phoenixville
 * Now US 44
 * Route 110, Hartford to MA
 * Now Route 159
 * Route 111, Waterbury to Willimantic
 * Now Meriden Road, Route 322, W. Main St, E. Main St, and Route 66
 * Route 112, Guilford to Middletown
 * Now Route 77 and Route 17
 * Route 113, Plainville to Hartford
 * Now Route 372, Route 71, and New Britain Ave
 * Route 114, New Haven to Durham
 * Now Route 17
 * Route 115, Hartford to Weatogue
 * Now Route 185
 * Route 116, Farmington to Granby via Simsbury
 * Now Route 10
 * Route 117, New Haven to Sandy Hook
 * Now Route 34
 * Route 118, New Haven to Milldale
 * Now Route 10
 * Route 119, NY to Danbury
 * Now US 6
 * Route 120, New Haven to Naugatuck
 * Now Route 63
 * Route 121, NY to Canaan
 * Now U.S. Route 44
 * Route 122, Newtown to Bridgeport
 * Now Route 25
 * Route 123, Cornwall to Avon
 * Now Route 4 and US 202
 * Route 124, Bridgeport to Danbury
 * Now Route 58
 * Route 125, Southbury to New Milford
 * Now Route 67
 * Route 126, Norwalk to Ridgefield
 * Now US 7
 * Route 127, Bulls Bridge to NY
 * Now Bulls Bridge Road
 * Route 128, Danbury to Torrington
 * Now US 202
 * Route 129, Gaylordsville to NY
 * Now Route 55
 * Route 130, Woodbury to Goshen
 * Now Route 61, Route 63
 * Route 131, NY to Sherman
 * Now Briggs Hill Road
 * Route 132, Cornwall to South Canaan
 * Now Route 43, Route 63
 * Route 133, north of Winsted to Granby
 * Now Route 20
 * Route 134, New Milford to Canaan
 * Now US 7
 * Route 135, New Haven to North Branford
 * Now Route 80, Route 139
 * Route 136, Danbury to Gaylordsville
 * Now Route 37, Route 39
 * Route 137, Pomfret Landing to Killingly
 * Now Route 101
 * Route 138, Farmington to Collinsville
 * Now Route 4, Route 179
 * Route 139, Killingly to RI
 * Now Route 101
 * Route 140, North Branford to North Guilford
 * Now Route 80
 * Route 141, Willimantic to Plainfield
 * Now Route 14, Route 14A
 * Route 142, Putnam to MA
 * Now Route 171, Route 169
 * Route 143, Ridgefield to NY
 * Now Route 116
 * Route 144, Wauregan to Brooklyn
 * Now Route 205
 * Route 145, New Milford to Shelton
 * old Ousatonic Turnpike (now gone)
 * Route 146, Mansfield Center to Storrs
 * Now Route 195
 * Route 147, Woodbridge to Southbury
 * Now Route 67
 * Route 148, East Haddam to North Westchester
 * Now Route 149
 * Route 149, Stafford Springs to MA
 * Now Route 190, Route 171
 * Route 150, Old Lyme to North Plain
 * Now Route 156
 * Route 151, Willington to MA
 * Now Route 320, Centre Pike, Route 197
 * Route 152, Washington to Cornwall
 * Now Route 45
 * Route 153, East Haddam to Norwich
 * Now Route 82
 * Route 154, Woodbury to Washington
 * Now Route 47
 * Route 155, Bulls Bridge to New Preston
 * Now Bulls Bridge Road, W. Meetinghouse Road, Barker Road, Cherniske Road
 * Route 156, Newtown to Brooksfield
 * Now Route 25
 * Route 157, Bristol to Farmington
 * Now US 6
 * Route 158, Redding Ridge to Newtown
 * old Newtown Turnpike
 * Route 159, New Milford to Washington
 * Now Route 109
 * Route 160, Unionville to Plainville
 * Now Route 177
 * Route 161, Bethel to Newtown
 * Now Route 302
 * Route 162, Berlin to New Britain
 * Now Route 372, Route 71
 * Route 163, Torrington to Burlington
 * Now Route 4
 * Route 164, Glastonbury to Manchester
 * Now Route 83
 * Route 165, Glastonbury
 * Now Route 94
 * Route 166, Vernon to Stafford
 * Now Route 30
 * Route 167, Haddam
 * Now Route 151
 * Route 168, Bozrah to Andover
 * Now Route 87
 * Route 169, Chester
 * Now Route 148
 * Route 170, Montville
 * Now New London Turnpike (local)
 * Route 171, East Haven to Branford
 * Now Route 142
 * Route 172, Waterbury to Bristol
 * Now Route 69
 * Route 173, Shelton
 * Now Route 110
 * Route 174, Winsted to MA
 * Now Route 183

Routes 301-399

 * Route 312, Torrington to Norfolk
 * Now Route 272