Statistics for occurrence #1 of “Middlesex County” in chapter 15 of Historic leaves, volume 4, April, 1905 - January, 1906:

...ary reaching from Miller's river to Burlington, Charlestown bounded with Lynn on the northeast, and with Boston on the Mystic river, as Chelsea was early a part of Boston. This most ancient town of Middlesex County was the third settlement in the limits of Massachusetts, outside of Plymouth plantation. The first Court of Assistants was held at Charlestown. In every line of business and commerce Charlestown ...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Middlesex County (Massachusetts, United States) 213 4 1 0 0 user votes
Middlesex County (Virginia, United States) 131 0 3 0 0 user votes
Middlesex County (Connecticut, United States) 0 0 0 0 0 user votes
Middlesex County (New Jersey, United States) 0 0 0 0 0 user votes

† This entity has been selected by the automated classifier as the most likely match in this context. It may or may not be the correct match.