A housing unit is owner occupied if the owner or co-owner lives in the unit, even if it is mortgaged or not fully paid for, All other occupied units are classified as renter occupied, whether or not cash rent is paid. Examples of units for which no cash rent is paid include units occupied in exchange for services rendered, units owned by relatives and occupied without payment of rent, and units occupied by sharecroppers.

In order to obtain data on Spanish- and Mexican/Americans for areas of the United States where most of them live, white persons (and white heads of households) of Spanish surname were distinguished separately in five Southwestern States (Arizona, California, Colorado, New Mexico, and Texas). In all other States, Puerto Rican persons (and heads of households) were identified. Puerto Rican comprise persons born in Puerto Rico and persons of native parentage with at least one parent born in Puerto Rico.

A housing unit is occupied if it was the usual place of residence for the person or group of persons living in it at the time of enumeration. Included are units occupied by persons who were only temporarily absent (for example, on vacation) and units occupied by persons with no usual place of residence elsewhere.