I'm going to make a 2016 presidential election map for the 124 states. Here's New England, New York, and New Jersey: (by the way, do you guys want Atlas colors or traditional colors?)
The splitting up of many Northeastern states definitely helps out the Republicans. They go from winning zero among these states to five (versus twelve for Democrats) even though the region maintains a Democratic lean.
Here's what the partisan leanings of each state are:
Lean Republican
New Hampshire - despite getting Winhall and Killington from heavily Democratic Vermont, the tiny size of the two towns and removal of Grafton County gives the Republicans a small but decisive lead, and NH would probably go from tossup to lean R overall without the most Democratic part of the state.
Empire (upstate NY) - Trump did decently here, and has a lead of over 100K (though not quite over 50%) and is able to win without the city hampering it down.
Long Island - similar story to Empire- no city gives the area a Republican lean.
Moderately Republican
(none yet)
Strong Republican
Maine (north-central ME, might be Moderately Republican) - composed of the best area for Trump in the state.
Aroostook - Trump had a 17 point margin of victory in this county.
Lean Democratic
North Massachusetts (coastal Maine) - although it has Portland, it still has many areas where Trump did well.
Rhode Island (southern RI) - surprisingly close.
South Jersey - the margin is only a few thousand votes D, so this would probably be a tossup overall.
Moderately Democratic
Connecticut - only state unchanged in the area.
Strong Democratic
North Jersey - 500K Democratic margin.
New York City - unsurprisingly, has a huge Democratic margin.
Providence - voted 57-36 Clinton-Trump.
Massachusetts - even without the islands and Boston, this state is still strongly Democratic (Clinton only does a few percentage points worse)
Boston - a city that is almost as D as Washington, D.C.
Essex - Not as D as Boston, but still too Democratic for a Republican to win.
Vermont - not a big surprise here.