Another individual cause operates especially upon the more able and intelligent classes and sends them to Northern cities. The restriction by "Jim Crow" legislation and by custom of the rights and privileges of persons of color in Southern communities leads some of them to migrate North. They long for a larger liberty for themselves and particularly for their children, which the hard conditions of Southern communities do not give. They come North to gain this and to escape the proscriptions.[15] They settle in the cities. A similar force probably operates in a few sections of the South to send Negro families to the security of the urban centers.[16] The final conclusion from these facts concerning the causes operating upon the Negro population has been clearly indicated in the above discussion. Such fundamental economic and social causes do not cease to operate suddenly. So far as the development of the South is concerned, the agricultural, industrial and commercial movement is in its infancy, and it will doubtless be of an indefinite growth. The secondary and individual causes will continue to play their part. The Negro will be affected in a manner similar to that of the Southern white population. Any rural improvement or "back-to-the-land" movement should recognize that along with the whites, Negroes will continue to migrate to the urban centers and that they will come to the cities in comparatively large numbers to stay. The problem alike of statesman, race leader, and philanthropist is to understand the conditions of segregation and oppositions due to race prejudices that are arising as a sequel to this urban concentration and to co-operate with the Negro in his effort to learn to live in the city as well as the country. Although it requires serious attention, the situation is a hopeful one. Improvement in the living and working conditions has its effect upon the health and morals of Negroes just as it has in the case of other elements of the population. Intelligence is essentially a matter of education and training. Good housing, pure milk and water supply, sufficient food and clothing, which adequate wages allow, street and sewer sanitation, have their direct effect upon health and physique. And municipal protection and freedom from the pressure of the less moral elements of the environing group go a long way toward elevating standards of morality. In spite of the limits which the neglect and prejudice of a white public sets to opportunities for improvement, Negroes do show progress along these lines. Speaking first of the health of Negroes in cities, an index is given in the general death-rate.[17] In the period from 1871 to 1904, the death rate for the white and Negro populations of several Southern cities is summarized by Mr. Hoffman.[18] Of the consolidated death-rate of the white population, he says,