The most quick way, which avoids a lot of New Brunswick is going down the Annapolis Valley way (about 233 kms, 145 miles), then getting on the Saint John Ferry. Going from Saint John to the border (Calais, Maine) about 114 kms (71 miles). Then Calais, Maine to Bangor, Maine is another 157 kms (98 miles). Then from Bangor, Maine to Portland, Maine it's another 207 kms (129 miles).
Halifax, Nova Scotia -> Ferry (233 kms) (145 miles)
Saint John, New Brunswick -> Calais, Maine (114 kms) (71 miles)
Calais, Maine -> Bangor, Maine (157 kms) (98 miles)
Bangor, Maine -> Portland, Maine (207 kms) (129 miles)
All in all, you'll probably be driving for a good 11 hours. You'll probably rack up a good 800 kms (497 miles).
About 560 miles.
The driving distance from Halifax NS to the Maine state line is about 544 km (338 miles).
The driving distance from Halifax, Canada to Maine (ME) is 496 miles / 798 km
The driving distance from Cherryfield, Maine to Halifax, Canada is 401 miles / 645 km
The driving distance from Portland, ME, USA to Belfast, ME, USA is 102.59mi / 165.1km
The driving distance from Portland, ME, USA to Acadia National Park, Maine, USA is 171.07mi / 275.31km
The driving distance is about 902km
The driving distance from Newark, New Jersey to Portland, Maine is 328 miles / 528 km
The driving distance from Philadelphia PA to Portland Maine is 408 miles
34.3 miles
17.2 miles
230 miles