Before the American Civil War, New Orleans was one of the largest cities in the United States, with a population of over 100,000. The federal government was funded by import and export duties and the states and local governments were funded by property taxes.
New Orleans was sensitive to property taxes. To make the job of the assessors easier, the assessors adopted a rule that said that property taxes were proportional to the front footage of the lot, that is, the length of the lot along its street. The depth of lots was fairly consistent due to the streets' fairly consistent layout. The rule was thus relatively accurate since land, not the structure, represented the value of the property.
To minimize property tax, lots were narrow but deep. As a result, houses were similarly narrow but deep. This is a striking difference from the contemporary ranch-style homes. The New Orleans house of that time became known as a shotgun house because it was said that you could stand in the front door and shoot a shotgun all the way through to the rear wall without hitting anything within. Hallways were avoided because they took up valuable room width inside the house.
The shotgun double became popular then. A shotgun double was two residences under one roof and the building was two rooms wide, instead of the shotgun’s single room width. The double has two front doors and the two residences share a common set of center chimneys. Each room had a fireplace for heat. This style saved the narrow alleys between each house that lead to the back yard as well as the construction cost of the multiple chimneys.
Citizens of New Orleans complained that their neighbor with a two-story house paid the same property tax as that paid by the owner of a one-story house. The assessors changed their rule to one that determined property taxes under a formula: the front footage times the number of stories the house had.
As a result of that rule change, the camelback house was born. A camelback house has a hump at the back; it was two stories tall in the back but only one in the front. In response, the assessors made a new rule that determined how far back the hump began before the house was determined to be a two story house.
Nevertheless, the property owners complained that the much grander camelback down the street paid the same tax as the single story house. In exasperation, the assessors made an entirely new rule: the tax would be based on the number of rooms within the house.
To the extent that anyone considered it previously, closets became totally unrealistic. A closet was counted as a room because a closet is an enclosed space with a door. So instead of closets, home owners used furniture to store clothes - the chiffarobe was born.
So, the New Orleans house is narrow and deep. It has no closets or hallways but every room has a fire place. City water and sewerage was added later so all the rooms that require this are at the back of the house at the site of the back porch.