In these dry elevated regions the heat is never oppressive in the day
and the nights are always cool. Day temperatures of 120° or more are
not uncommon in the valleys in July and August, but the humidity is so
slight that such high readings do not produce the discomfort the figures
might imply. In his calico shirt and breeches the Navaho is quite
comfortable, and in the cool of the evening and night he has but to add
a blanket, which he always has within reach. The range between the day
and night temperature in summer is often very great, but the houses are
constructed to meet these conditions; they are cool in hot weather and
warm in cold weather.

The extreme dryness of the air has another advantage from the Indian
point of view, in that it permits a certain degree of filthiness. This
seems inseparable from the Indian character, but it would be impossible
in a moist climate; even under the favorable conditions of the plateau
country many of the tribes are periodically decimated by smallpox.


HABITS OF THE PEOPLE

The habits of a people, which are to a certain extent the product of the
country in which they live, in turn have a pronounced effect on their
habitations. New Mexico and Arizona came into the possession of the
United States in 1846, and prior to that time the Navaho lived chiefly
by war and plunder. The Mexican settlers along the Rio Grande and the
Pueblo Indians of the same region were the principal contributors to
their welfare, and the thousands of sheep and horses which were stolen
from these people formed the nucleus or starting point of the large
flocks and herds which constitute the wealth of the Navaho today.