Although city planning is not a new art it is only within recent years that American cities have given much attention to it. For many decades the cities and their suburbs were allowed to grow haphazard. What was once a country highway became a village road, then the main street of a town, and finally the chief business thoroughfare of a large city. To have widened it in early days would have been cheap and easy; but when a city has grown up on both sides of it the project becomes too expensive. Lack of planning is responsible for much of the traffic congestion with which the cities are wrestling nowadays. [Sidenote: The great importance of streets.] =The Streets.=—The streets are very important factors in the daily life of every community, far more so than we commonly realize. They are the city’s arteries. On their surface they carry vehicles of every sort. Their surface also affords locations for lamp posts, telephone poles, hydrants, and many other instrumentalities of public service. Underneath the street surface are sewers, water mains, gas pipes, and conduits; overhead are wires and signs and balconies. The streets give access to the shops and houses; they are likewise the principal channels for light and air, both of which are essential to life in the buildings alongside. Nearly every form of public service depends upon the streets; without them private property would have little or no value. About one-third of all the land in the city is occupied by the streets, so that proper street planning becomes a matter of great importance to the community.[81] [Sidenote: The layout of streets.] In most American cities the streets are laid out in rectangular form, with long, broad avenues running one way and narrower cross-streets the other. This means that each intersects the other at right angles and the city blocks become squares like those of a checker-board. This plan has been widely used in America because it takes less land for streets than any other plan would require and it makes all building lots of convenient rectangular shape.[82] The chief objection to this gridiron plan is that it makes traffic more congested at the junction of important thoroughfares. It also gives a sameness to the appearance of all the streets and hampers the development of architectural variety. European visitors often comment on this. Street after street in the shopping or residential districts all look alike to the stranger; all have been laid out with a pencil and ruler, the same widths (or nearly the same); every lot of land is of the same size; and the long rows of houses seem to be all of the same type. In the cities of Europe, on the other hand, the streets are more often curved or winding; some are very broad and some very narrow, so that each street has its own individuality. To some extent American cities are now laying out diagonal and winding streets in their newer suburbs on the principle that picturesqueness ought to be combined with utility.