The so-called 'shotgun house' was actually built throughout the United States during the 19th Century, for the purpose of keeping property taxes low. The style of building is thought to have been imported from the West Indies, and arrived in the U.S. in the early 19th Century. It is thought to have been based on an African design style. Though it entered the United States through New Orleans around the time of the Jackson purchase, it eventually spread through the country
The classical shotgun house was only one room wide, and three rooms deep. The gable of the house is oriented towards the street, and there is usually a front porch. There were no side-facing windows, as the houses were often built quite close together, and this would negate any privacy for the home owner. Doors connected the three rooms, and the doors were aligned through the house. This is where the folk etymology shotgun house is derived from; the story went that if you opened all the doors in the house, you could fire a shotgun straight through the front door and hit a target out the back door.
Several variations on the shotgun house existed. The camelback had a second story, set back from the street-facing entrance. Another variation, intended to provide more privacy, introduced a hallway running along the long side of the house, so that the interior rooms opened onto the hallway instead of being walkthroughs. The double shotgun consisted of two shotgun houses built back-to-back, and was a convenient way of maximizing space usage (and thus income!) on narrow, densely developed lots.
As one of the earliest usages of the shotgun style was in the construction of slave cabins in the South, shotgun houses were initially associated with the homes of African-Americans, particularly with urban-dwelling free blacks during the pre-Civil War era. After the Civil War, the style of architecture was more generally used in the homes of the lower and middle class, and continued to be employed until the 20th Century.