The area of timber land owned by the states, by corporations, and by individuals is very much greater than that contained in the national reservations. It is here, moreover, that the greatest amount of waste is taking place. Forest fires, most of which are due to carelessness, burn up enormous quantities of timber every year. The states which still possess considerable forest resources, such as New York, Minnesota, and California, are also adopting the policy of creating reservations and everywhere more effective measures are being taken to prevent destruction by forest fires. These measures include the maintenance of fire patrols, the construction of fire-breaks on the ridges of hills, the clearing out of underbrush, and the stricter supervision of camping parties. Timber, fortunately, is a natural resource which can be replaced. Lands which have been cut-over can be reforested and used to supply timber for future generations. Large trees take a long time to mature, however, and the lands which are being planted with seedlings today will not be yielding material for the sawmill until the middle of the twentieth century has faded into the past. Both the national and state governments are now reforesting on a large scale. To some extent private corporations and individuals have followed their lead. [Sidenote: Harbors, lakes, and waterways.] =Other Natural Resources.=—All the nation’s wealth does not come, however, from the fields, the mines, and the forests. In fisheries America leads the entire world. The harbors and the waterways of the country are as important to commerce as the soil is to agriculture. No other country is better provided with natural harbors, lakes, and navigable rivers than the United States. All the largest cities are located upon them, and were it not for the waterways, we would not have the great cities. Run over in your mind the ten or fifteen largest cities of the United States and see if you can name any that are not situated on one of the oceans, the Great Lakes, the great navigable rivers, or on the Gulf of Mexico. It is not a mere accident that none of the great industrial centers are without facilities for trade by water. Geography, not man, determines for the most part the situation of all great industrial communities. Water power is another natural heritage. [Sidenote: Water power.] From the giant Niagara to the smallest cataract, thousands of these water powers have been harnessed and made to function as the servant of man, running factories and generating electricity. Water power does the work of coal.[155] Its presence has often determined the location of large industries. [Sidenote: How geography determines a nation’s progress.]