In anticipation of widespread power outages, Gov. Paul LePage signed a "limited emergency declaration" so power crews from other states and Canada can help the state prepare for Sandy. The declaration also extends the hours that power company crews can drive.
Gov. Deval Patrick declared a state of emergency for the Bay State.
Hoping to avoid the kind of criticism utilities received after last year's Hurricane Irene and other storms, Patrick said utilities plan to pair tree removal and power restoration crews -- rather than having them work separately -- so that work can be done more efficiently.
The city of Boston announced that schools will be closed Monday.
Obama also declared a state of emergency for Massachusetts.
Like several neighboring states, Maryland could see as much as a foot of rain in some areas -- a major reason the state has declared a state of emergency.
Besides flooding, strong winds are expected to cause significant power outages. The Baltimore Gas and Electric Company, for instance, says several hundred thousand customers could be affected.
Public schools in Baltimore, Montgomery and Prince George's County will be closed Monday.
In the coastal city of Annapolis, city crews distributed sandbags to residents and businesses to help them prepare for flooding.
President Obama declared a state of emergency in Maryland on Sunday.
Sandy could bring winds of up to 60 mph and dump 2 and 4 inches of rain to parts of the Granite State -- likely starting Monday, Gov. John Lynch's office said.
"While the exact path and severity of the storm remain uncertain, it is clear New Hampshire will experience a significant weather event and I urge everyone to be prepared," Lynch said.
New Jersey was the first to announce mandatory evacuations. The state's barrier islands from Sandy Hook south to Cape May must be cleared out, along with Atlantic City's casinos.
"We have to prepare for the worst here," Gov. Chris Christie said. Tolls have been suspended on the northbound Garden State Parkway and the westbound Atlantic City Expressway so people in those areas can leave more quickly, he said.
All state offices will be closed on Monday, with only essential employees expected to report to work, Christie announced.
New Jersey Transit came to a halt and will remain suspended indefinitely.