Backstory and Setting
I'm forging an alternate history set in the year 2012, a horrible zombie virus is sweeping across America, it spreads extremely quick and is incurable. The infected are basically Dawn of the Dead zombies that are smart, a deadly threat. The Center for Disease Control has decided to save as many of the American people as humanly possible. While the states on the West Coast and central America have already fallen into chaos, the remaining states of the East coast can still be saved; over 100 million people. The government has decided to set up shop in the North-Easternmost states of New York, and have already blown up the bridges and entrances to the island. Now Military rescue Helicopters are spreading across the "Survivor Zone", based on Aircraft carriers.
The Question
While figuring out a number for survivors that would come to live in the safe zone, I hit a mental block as population density and survival (at least in terms of food and water) are one of my many weak spots. The safe Zone is over 350000 km squared and has a current population of over 40 million after riots. Assuming that each person is allowing an average of 1000 square feet and the rescue missions have a 6 in 10 success rate, how many people can the government realistically house, feed and keep alive in the safe zone?