=Need of Municipal Government.=--The systems of local government described in the preceding chapter are those which have been devised mainly for rural communities, that is, communities containing a scattered population engaged principally in agricultural pursuits. In a sparsely settled community the governmental needs of the people are comparatively few, and a simple governmental organization is sufficient for supplying those needs. In a densely populated community, however, a more complex and differently organized form of government must be provided. When, therefore, a community becomes so populous that it cannot be governed effectively by town meetings, small boards, and the other forms of political machinery described in the previous chapter, it is incorporated as a municipality, that is, the state gives it a charter which confers upon it special powers and privileges and provides it with a somewhat different type of local government for the exercise of those powers. The minimum population necessary to constitute a city varies in the different states. They all require, however, that there must be a considerable number of inhabitants occupying a comparatively small area of territory, before the community can be incorporated as a city. In Illinois, for example, any community having at least 1,000 inhabitants resident within an area not exceeding four square miles may become a city. In some other states, a population of not less than 5,000 is required, while in some a still larger number is required. The census bureau of the United States, for statistical purposes, has at different times taken 8,000 and 2,500 as the minimum population required to constitute a city.