336 THE TREND OF THE RACE 
town is ruinous. The large town is a far shining light house 
whose lamp consumes a mighty deal of fuel.” In cities humanity 
is exposed to unnatural conditions of life. Frequently inhabitants 
are crowded together, with an inadequate supply of fresh air, 
exposed to increased risks of contagion and inducted into habits 
of vice that deteriorate their posterity as well as themselves. The 
effect of these untoward agencies is reflected in the rate of mor- 
tality which is generally higher in urban than in rural commu- 
nities. We cannot, however, in all cases accept the mortality rate 
of cities as a reliable index of their healthfulness. As a measure of 
the actual influence of the city upon the duration of life it may be 
too high or too low. The presence of hospitals and asylums, 
orphanages and homes for the aged occasion a rise in the general 
death rate. On the other hand, barracks and institutions of 
learning, which contain many people at an age when the death 
rate is low, tend to produce an unduly favorable impression of the 
general salubrity of the city in which they occur. The same 
influence is exerted by the various industries which create a 
demand for the employment of men and women in the prime of 
life. On the whole, the death rate in cities tends to be abnormally 
low, because there are, as a rule, relatively more people of adoles- 
cent or middle age than in the country. The presence of many 
children of an early age naturally raises the general death rate, 
and where the birth rate has declined, as it has done to so great an 
extent in many cities, the general death rate becomes corre- 
spondingly reduced. A city may for various reasons have a very 
low death rate and nevertheless be a very unwholesome place 
in which to live. 
Notwithstanding the causes which tend to reduce the rates 
of urban mortality as they are commonly expressed, the death 
rates of cities generally have been, and in some countries still are, 
greater than that of adjacent rural communities. This is shown 
for the United States in the following table giving the death rates 
of urban and rural communities in the registration area: 
