The purpose of this part is to establish special programs of assistance to nonprofit private locally initiated community development corporations which (1) are directed to the solution of the critical problems existing in particular communities or neighborhoods (defined without regard to political or other subdivisions or boundaries) within those urban and rural areas having concentrations or substantial numbers of low-income persons; (2) are of sufficient size, scope, and duration to have an appreciable impact in such communities, neighborhoods, and rural areas in arresting tendencies towa