CT border in Sturbridge to MA 131 in Sturbridge.
Route 15 was originally an extension of CT 15 from the state line in Holland up to US 20 in Sturbridge. It first appears on my 1933 map.
Massachusetts upgraded their section of Rt 15 between 1950 and 1953. Connecitcut completed their 4-laning by 1956, and the road was extended up to the new Massachusetts Turnpike at interchange 9. No intechanges are shown on 15 on this map.
Between 1959 and 1961, Interstate 84 was designated along Rt 15. My 1961 map shows the 84 designation as a proposal; the 1966 map shows MA 15 from the state line to US 20 as multilane divided by not controlled access.
By 1971, the 84/86 switch was on. 15 was still not completely controlled access. Up to about where current exit 1 is located was considered controlled. 1972 showed completed access control, with exits as US 20 and what is now Exit 1.
Between 1974 and 1975, Westville Reservoir was drained. Before 1989, exit 2 would be built in the former lake bed.
My 1979 state map does not show MA 15 on the highway; just I-86. In 1984, I-86 was officially dead and the road was re-renumber back to 84. The 1999 official state map also does not show 15; however the 2001 shows it as a road just west of I-84 as it crosses the border, crosses I-84 at exit 1, then parallels I-84 up to MA 131 in Sturbridge. Gus Steeves, who lives in the area, informed me that the former Rt 15 is now just ‘Haynes St.’
There is also a MA 15 listed in the state traffic data logs as Rt 15. It is an extension of RI 15 to MA 152 in Seekonk.
Kurumi’s CT 15 entry