In inFamous 2 for the PS3, there is a trick you can do to gain early access to the Flood Town area if you feel like exploring.
Go into the Mission Editor and move the marker to one of the bridges that connects New Marais to Flood Town. Make sure to move the marker up above the bridge by about 50 to 60 feet.
Now when you spawn in the game, you’ll spawn in this spot in the air. All you need to do is use your thrusters to float into Flood Town.