| US Route Number | State | Type | Intersection | Point to Point | Accumulated | Remarks |
| 1 | Massachusetts | Regular | State Line | 0 | 0 | NONE |
| 1 | Massachusetts | Regular | Danvers | 21 | 21 | Crosses I-95 |
| 1 | Massachusetts | Regular | Lynnfield | 6 | 27 | Crosses I-95 |
| 1 | Massachusetts | Regular | Boston | 12 | 39 | Joins I-93 |
| 1 | Massachusetts | Regular | Boston | 3 | 42 | Crosses I-90 |
| 1 | Massachusetts | Regular | Canton | 16 | 58 | Joins I-95; I-93 ends |
| 1 | Massachusetts | Regular | Dedham | 3 | 61 | Leaves I-95 |
| 1 | Massachusetts | Regular | Sharon | 7 | 68 | Crosses I-95 twice |
| 1 | Massachusetts | Regular | Plainville | 8 | 76 | Crosses I-495 |
| 1 | Massachusetts | Regular | N. Attleboro | 7 | 83 | Crosses I-295 |
| 1 | Massachusetts | Regular | Attleboro | 4 | 87 | Crosses I-95, State Line |
| 1 | Connecticut | Regular | State Line | 0 | 0 | NONE |
| 1 | Connecticut | Regular | Jct. W. Pawcatuck | 4 | 4 | NONE |
| 1 | Connecticut | Alternate | Jct. W. Pawcatuck | 0 | 0 | Route begins, leaves U.S. 1 |
| 1 | Connecticut | Alternate | Stonington Borough | 1 | 1 | NONE |
| 1 | Connecticut | Alternate | Jct. E. Mystic | 1 | 2 | Route ends, rejoins U.S. 1 |
| 1 | Connecticut | Regular | Jct. E. Mystic | 1 | 5 | U.S. 1 Alt. rejoins & ends |
| 1 | Connecticut | Regular | Mystic | 3 | 8 | NONE |
| 1 | Connecticut | Regular | Groton | 7 | 15 | Joins I-95 |
| 1 | Connecticut | Regular | New London | 1 | 16 | Leaves I-95 |
| 1 | Connecticut | Regular | Waterford | 3 | 19 | NONE |
| 1 | Connecticut | Regular | Flanders Village | 6 | 25 | Crosses I-95 |
| 1 | Connecticut | Regular | Old Lyme | 9 | 34 | Joins I-95 |
| 1 | Connecticut | Regular | Jct. E. Old Saybrook | 1 | 35 | Leaves I-95 |
| 1 | Connecticut | Regular | Jct. W. Guilford | 20 | 55 | Crosses I-95 |
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