The influence of topography may be summarized by saying that level land attracts business, moderate elevations attract residences, land below the normal level attracts transportation lines, and filled-in land is generally used for warehousing, man-ufacuring and cheap tenements.

The main direction of city growth is usually controlled by topography. For example, the cities at the west end of harbors or on the west side of rivers grow west, as Boston, San Francisco, St. Louis, Omaha, Minneapolis; cities on the east side of harbors or rivers grow east, as Columbus, St. Joseph, Memphis, Grand Rapids, Seattle, and similarly New York, Philadelphia, Detroit, New Orleans, Milwaukee, Indianapolis grow north; and Louisville, Kansas City, Savannah, Houston grow south. The impression that the points of a compass affect the direction of city growth is based on the statement that the majority of English and German cities are growing west, owing to the prevailing west winds which drive away the dense smoke from soft coal and render the west end of these cities the preferable residence sections. No such general tendency, however, exists in this country. As to their laying out, cities may be divided into two classes, those which have grown up without any definite ground plan and those whose ground plan has been laid out in advance of growth. The cities which have grown up haphazard exhibit a tangle of narrow and crooked streets of varying and irregular size, evolved from cow paths or old trails, whose directions were originally influenced by trifling obstacles, such as hillocks, rocks or clumps of trees. These first streets left large tracts between them, which were later pierced by irregular streets or lanes laid out for the convenience of the owner of the tract, and without consideration for the general interests of the city.

Example of diagonal avenues superimposed on rectanglar platting. Washington.

Example of diagonal avenues superimposed on rectanglar platting. Washington.

Irregular platting in old sections. Rectangular platting in new sections, especially in Back Bay District, Boston.

Irregular platting in old sections. Rectangular platting in new sections, especially in Back Bay District, Boston.

Where a plat has been laid out in advance, long, straight streets of even width, at right angles to each other, are found, leaving rectangular blocks for building sites. The older cities with marked modern growth, such as Rome and Athens, New York, Boston and Baltimore, exhibit almost uniformly an old centre of crooked streets, surrounded by modern rectangular plats, this change proving the general appreciation of the advantages of the rectangular method. Some cities, however, have never changed to rectangular platting, among them being Atlanta, Los Angeles, Salem and Lynn.

Plat of Savannah showing unusual percentage of park and street area. Plan said to have been derived from Bunyan's description of the Heavenly City.

Plat of Savannah showing unusual percentage of park and street area. Plan said to have been derived from Bunyan's description of the Heavenly City.

A number of the older cities originated with a small rectangular plat, surrounded later by rectangular additions, as Philadelphia, New Orleans, Cleveland and Cincinnati, while the newest cities have generally started with widespread rectangular platting, as Birmingham, Sioux City, Tacoma and Topeka. An exceptional instance would be Memphis, starting with a small rectangular plat, extended later by irregular streets, a reversion recalling the contrast between ancient Alexandria in Egypt with its rectangular plat, and modern Alexandria with irregular laying out.