RI line in Attleboro to NH line in Salisbury via Waltham.
First appears in 1958 on the highway up to the New Hampshire border. Between 1959 and 1961, was listed as under construction from the RI line to North Attleboro, proposed to 128 and proposed north of Boston to near Danvers. By 1966, the section south of Boston was completed.
Inside 128, though, it is unclear what was and wasn’t 95. It definitely was on north of the Harbor tunnels and up the Northeast Expressway. The highway was proposed to head more or less directly into the heart of Boston from the Canton interchange with 128, roughly paralleling Hyde Park Ave to Washington St and then up Washington to the infamous Inner Belt. North of town, 95 was proposed to run through southern Saugus, through Lynn Woods and into Peabody. It would have crossed 128 west of the current interchange and paralleled US 1 to the east. It appears construction actually began on the section north of Revere to Ballard St in Saugus.
In 1972, the southern highway proposal (the Southwest Expressway) was abandoned  and I-95 was routed onto MA 128 & MA 3 from Canton to Boston. This was a short-lived proposal; by 1975 I-95 was cosigned with 128 from Canton to Peabody. 95 was built to the east of US 1 through Peabody to Danvers. The final piece of the puzzle, the interchange in Peabody between 128 and 95 north, was opened between 1986 and 1995.
 Yes, I know that 128 technically exists only from Peabody to Gloucester. But the signs show it multiplexed with 95 and everyone calls it 128 anyways. Want to know the gory details? Go to the MA 128 page.
 Planning the City Upon a Hill by Lawrence W. Kennedy.