A head to head comparison of the Massachusetts 2012 General Election gives us an idea of the break down of the voters.    

Barack Obama received 1,901,280 (61%) votes, beating Mitt Romney who gained 1,178,240 (38%) by 723,040 votes in Massachusetts.

Barack Obama won 257 counties whereas Mitt Romney won 94 counties in the total of the 351 counties in the State of Massachusetts.

Presidential General Elections

During the 2012 General elections, over 122M total number of votes were cast. Barack Obama got 62,614,654 (62.6 Million) over Mitt Romney's 59,141,654 (59.1 Million). He won the popular vote by 3,472,979 (3.4 Million). His victory in the State of Massachusetts (with 1,901,280 votes) represents 2.9% of his popular vote victory. The remaining 49 states contributed to the remaining 97.1% popular votes victory.

Top 15 Counties in Primary Elections vs General Elections

All Candidates (General Elections)

These 15 counties play an important role in these Primary elections. If a candidate, can get a sizable majority in the larger counties (Boston, Worcester, Springfield), it is still possible for other candidates to catch up, given the vast amount of counties that are there in the State of Massachusetts.

Top 15 Counties Comparison in Primary Elections vs General Elections

General Elections
Barack Obama

General Elections
Mitt Romney

Boston, Worcester and Springfield, three of the larger counties, voted in favor of Barack Obama giving him a 203k vote advantage. However, Obama's steady win in the less dense counties was enough to maintain that difference, making him gain an upper hand in the State of Massachusetts.

Related References: 2016 Massachusetts Primary Election Story, 2016 Massachusetts General Election Story, 2020 Massachusetts Primary Election Story, 2020 Massachusetts General Election Story