Having visited and lived in numerous states throughout the U.S., I've noticed there tends to be a dominant theme in the style of architecture in different parts of the country. In New Orleans, a predominant style of house I noticed while watching the documentary Trouble the Water and HBO series Treme was the "Shotgun" style. While the Shotgun house has been built in other areas outside New Orleans, it was originally popularized in this city.
The term Shotgun house has an unknown origin, but the common story relates to being able to fire a shotgun through the open front door of a house and having the shot exit through the back door since all the doors line up. Because the amount of land available in New Orleans was limited, most lots were usually a 30 foot width. This limitation of space for constructing larger residences precipitated the building of the narrow shotgun house. Following the end of Reconstruction, New Orleans experienced a growth spurt. Thousands of shotgun houses were built in the late 1800's. This style of house continued to be built until the 1920's.
The houses were built in three different types: single, double, and camelback. A single is a by itself stand alone residence. It has windows and doors at the front and back. Some examples did have windows on the side. The double shotgun is a two unit home that shares a common wall down the middle. This was the example of house Kim and Scott Roberts lived in before the flood from Hurricane Katrina. The last is is the camelback. The camelback has a small bedroom built on as a second floor to get more room out of the small dwelling. This "hump" on top gives the camelback its name.
Though the houses were fairly basic in design, there was room for a bit of flair from ornamentation. The roof vents and brackets that held up the roof over the front porch were usually quite ornate. The protruding roof over the front door created a covered porch. This in turn made an outdoor room for hot summer days and nights that better enabled visiting with neighbors. Kim and Scott's neighborhood exemplified this tradition of hanging out and visiting with neighbors on the front porch.
Although many of the shotgun houses were destroyed in the flood, there are many being salvaged. One example is shown on the This Old House wed site. http://www.thisoldhouse.com/toh/tv/house-project/overview/0,,20152647,00.html