Since 1990 the "other" category has included houseboats, railroad cards, campers, vans and caves and was intended to be living quarters.
In 1940, "other" units included trailers, tourist cabins, mobile homes and boats whose occupants had no other usual place of residence.
BOC has counted the number of units in a structure since 1940, and has counted mobile homes and trailers since 1950.
In 1970 and 1980, these data were shown only for year-round housing units. In 1990, these data are shown for all housing units.
In 1980, the data were collected on a sample basis.
The category, "Boat, tent, van, etc." was replaced in 1990 by the category "Other" (see above). In some areas, the proportion of units classified as "Other" is far larger than the number of units that were classified as "Boat, tent, van, etc." in 1980.