=Growth of Cities.=--One of the most remarkable political and social facts of the past century was the growth of towns and cities. When the Constitution of the United States went into operation there were but thirteen cities in the whole country with populations exceeding 5,000 each. Only about four per cent of the people then lived under urban conditions: rural life was the rule, and city life the exception. Since the middle of the last century, however, there has been a remarkable change in the relative proportion of the total population living in the cities and in the country. According to the federal census of 1910 there were 1,232 cities in the United States with a population of more than 5,000 each, and in them lived 42 per cent of all the people. The number is now considerably larger. It is estimated that 90 per cent of the people of Massachusetts now live in cities of over 5,000 inhabitants, and in a few other states the urban population constitutes more than two thirds of the whole. More than half the population of New York state is now found in the city of New York alone. Even in several states of the West, as Illinois, more than half the population is now living under urban conditions. What is even more remarkable has been the rapidity with which many American cities have grown to their present size. Thus New York in a period of 100 years grew from a city of 50,000 inhabitants to a city of more than 4,000,000. The growth of Chicago was even more rapid. In 1907 there was still living in that city the first white person born within its present limits. This person saw Chicago grow from a petty prairie village to a city of more than 2,000,000 souls.