Plank Country

Plank Country is the first chapter of the campaign Swamp Fever in Left 4 Dead 2. The map begins with the Survivors leaving a derailed train that fell in front of a small town, which they had been using as a temporary safe room. The townspeople, who had been resisting both help and refugees, believed that they could barricade themselves in, seeing as it bordered a swamp. Unfortunately, judging by the lack of other Survivors, the plan failed, and everyone has either been killed, infected, or simply left.

Campaign
The box car has basic starting supplies; four first-aid kits and tier 1 weapons. Considering the fact that the train hinders progress further down the highway, the only way to go is through the abandoned town. The Survivors head through a village of shacks, and eventually reach an old cable-ferry where the crescendo event kicks in. Not only are the Infected attracted to the sound as it moves toward the Survivors, but they keep coming while the ferry goes back. In addition the survivors can fall into the river to their deaths. After the event is over, the group wanders through the swamp until they find the safe room at the end of the chapter.
 *  This is one of the few most likely times for a Tank appear. If you hear either before this, get ready as you will, and try to spare a Molotov or a Bile Bomb for the Tank. 

The Survivors
Now that humans are controlling the Special Infected, things can only get harder. However, they can't spawn until you leave the campsite area. That doesn't mean that you should let them have a good chance to find just the right spot, though! Hurry up and get your supplies, and get running!

This level can be very tricky for the human controlled survivors, since the infected are not bots anymore. There are some "instant kills" spots in the crescendo event area. Also, tanks may spawn after leaving the ferry.

The Infected
Chargers: You can make instant kills here. For you to finish off unlucky survivors, you must charge them into the water, making them fall to their death.

Trivia

 * At the beginning of the level, Ellis complains to Nick about why he shot the helicopter pilot. Then they argue that the pilot was a zombie and that "he wouldn't help us very much" during that time. This seems to be a running joke with the Survivors.
 * Ellis apparently thinks that the infected pilot could still have flown the helicopter judging from what he says during the argument.
 * The helicopter can be seen behind the train that is at the beginning of the chapter where you start on, If you also look at the Chopper via Noclip you can see that there is unfinished part of the map and when you look through the train you can still see the unfinished part of the map.
 * The crashed Helicopter is the crashed News Chopper 5 model that was used in Crash Course.
 * There is a jukebox Easter egg in this level.
 * Near the ferry Crescendo event, there is a Charger strung up by all limbs. It is also interesting to note that the Charger is hung in the shape of a Lambda, the logo of Valve's Half-Life series.
 * A glitch can happen near the ferry Crescendo event where a charger can push a survivor into the water and cause them to get stuck only to eventually die once the other survivors move across on the ferry
 * The PC version of Plank Country has a glitch in Versus mode that gives the survivors 500 points upon activation of the crank that calls over the river boat. The glitch also temporarily prevents the infected players from spawning.
 * The gas station at the beginning of the level has prices over seven dollars. This, needless to say, is outrageous. It is worth noting, however, that there was gas price gouging in the immediate wake of Hurricane Katrina, and the impending zombie apocalypse would have easily caused a panic and created a high demand for gasoline.
 * During a Versus match the Charger can easily charge a survivor straight to the lake, killing him instantly.
 * The scenario at the beginning of the level is almost exactly the same as the one for Crash Course which involves one of the Survivors shooting the pilot of the rescue vehicle, with both pilots piloting helicopters, because of pilot being infected. However, In Left 4 Dead 2, the complainer (Nick) kills the pilot while the youngest one (Ellis) complains about that the pilot is dead, while in the original Left 4 Dead, the youngest one (Zoey) kills the pilot and is being yelled at by the complainer (Francis).
 * It should be pointed out that in Versus, if an Infected player jumps into the lake in Spawn mode, it will still kill them.