One of my earliest recollections of a canvas covered geography is the prime fact which is Pittsburgh,--that here the Allegheny and Monongahela rivers unite to form the Ohio. Huge economic foundations buttress this fact (oil and gas and clay and iron and coal). History in the making has rolled it into new shapes and a changing significance. The junction is the great left fist of the Father of Waters. The three rivers give the town common cause and intercourse with the Atlantic coast ranges to the east, and the mid-continental bottom lands, north and south, to the west. Their waters carry the ores and fill the boilers and douse the hissing billets of the steel makers. They are not easy overlords, this triumvirate of rivers. They carry fever which scotches one town and the next. They rise a bit too far and the fires are out, the streets flooded. But grudgingly and inevitably, they yield mastery. They are dammed and sluiced and boiled and filtered to suit the demands of navigation and power and temperature and thirst.
The mastery they yield is to another current--the eddying peoples which make up the community and all its works--a current more powerful and mysterious than the bulk of brown waters. The War Department engineers can tell you the exact number of cubic feet which slide past either side of the Point every minute. The sanitarians can give you the number of bacteria, friendly or plague-besetting, which infect any cubic centimeter. The weather man in a high building can forecast the exact stage which the water will register hours hence. But what of the people?--they have largely taken themselves for granted. They have rarely taken the time to test their own needs or consciously gauge the destination of the currents that possess them. They are here--the strong, the weak, the cowed, the ambitious, the well equipped and the pitiful. They jostle and work and breed. For the most part they run a splendid course. But they do not keep tally, and their ignorance means sorrow and death and misunderstanding.
To give a little help to those who are trying to understand, and measure these currents, and deal with them as intelligently as the locks and channels of the rivers are dealt with, has been the purpose of the Pittsburgh Survey. Such chartings as we have attempted have been of these living waters.