Subways were shut down from Boston to Washington, as were Amtrak and the commuter rail lines. About 1,000 flights were canceled at each of the three major airports in the New York City area. Philadelphia International Airport had 1,200 canceled flights, according to FlightAware, a data provider in Houston. And late Monday night, Mayor Bloomberg said cabs had been instructed to get off New York City roads.NYT 1) Sandy hurts Obama.  As Larry Bartels wrote about a few months ago, incumbent presidents can be punished for natural disasters, including floods.  Of course, a lot hinges on whether serious damage hits the key battleground states in Sandy’s path: Virginia and Pennsylvania, plus probably New Hampshire and maybe parts of Ohio.  Given Obama’s apparent lead in Pennsylvania, it’s less likely that Sandy’s damage could swing that state against him.   2) Sandy helps Obama.  Some research by John Gasper and Andrew Reeves finds that while both presidents and governors are punished for natural disasters, they are rewarded for a proactive response to those disasters.  President Obama has declared  that location a disaster area (and therefore eligible for federal disaster funds). 3) Sandy limits early voting, possibly hurting Obama’s chances.  David Axelrod is already suggesting this could happen.