Should a resident who lives in two homes in two different cities within the same country shorten his prayers when traveling to one of them, or should he offer them in full?

If a person uses two houses as residences, then it is not permissible for him to avail himself of the concessions of travel (such as shortening prayers) while he is residing in either of the two houses. However, when traveling between the two houses, he may avail himself of the concessions of travel if the distance between them is a distance that permits shortening prayers, which is approximately eighty kilometers.