The establishment of a new industry, especially if it displaces the previous economic base, may also make for a more or less complete change of population without greatly modifying the size of the community. This condition is exemplified in many of the small towns of the state of Washington which have changed from lumbering to agriculture or from one type of agriculture to another. In many cases few of the previous inhabitants remained after the invasion of the new economic base. As a community increases in size, however, it becomes better able to accommodate itself to invasions and to sudden changes in number of inhabitants. The city tends to become the reservoir into which the surplus population drains from the smaller communities round about. V. ECOLOGICAL PROCESSES DETERMINING THE INTERNAL STRUCTURE OF COMMUNITY In the process of community growth there is a development from the simple to the complex, from the general to the specialized; first to increasing centralization and later to a decentralization process. In the small town or village the primary universal needs are satisfied by a few general stores and a few simple institutions such as church, school, and home. As the community increases in size specialization takes place both in the type of service provided and in the location of the place of service. The sequence of development may be somewhat as follows: first the grocery store, sometimes carrying a few of the more staple dry goods, then the restaurant, poolroom, barber shop, drug store, dry-goods store, and later bank, haberdashery, millinery, and other specialized lines of service.[48] The axial or skeletal structure of a community is determined by the course of the first routes of travel and traffic.[49] Houses and shops are constructed near the road, usually parallel with it. The road may be a trail, public highway, railroad, river, or ocean harbor, but, in any case, the community usually starts in parallel relation to the first main highway. With the accumulation of population and utilities the community takes form, first along one side of the highway and later on both sides. The point of junction or crossing of two main highways, as a rule, serves as the initial center of the community.