Its more likely he spoke with an English accent, as his parents were from that stock and the influx of the Irish, which was mainly Protestant (before 1820), wasn't the same influence as it became later. read more
But in those times, for example, John Adams used to ride to the Congress in Philadelphia from Boston on horseback. That took a long time. There wouldn't be a huge and rapid change of dialect like there is now. read more
The Boston accent is the local accent of Eastern New England English spoken specifically in the city of Boston, its suburbs, and much of eastern Massachusetts. Eastern New England English also traditionally includes New Hampshire and Maine, though some uniquely local lexical characteristics appear only in eastern Massachusetts. read more