A project or undertaking, including the real, personal, and mixed property involved, qualifies as a public purpose project if it is planned, acquired, owned, developed, constructed, reconstructed, rehabilitated, repaired, renovated, or improved with the financial assistance of the Administration or the assistance of federal low-income housing credits authorized by the Internal Revenue Code, and it is: eligible wholly or partly for federal low-income housing credits; or located in a distressed area designated under subsection (e) of this section. Except as provided in subsection (c) of this section, a public purpose project: shall provide in substantial part for existing or new housing; and may include: any improvements, such as streets, roads, sewer lines, and water lines; and public or private commercial, educational, cultural, recreational, community, or civic facilities. A public purpose project may include a greater proportion of public or private facilities if the Secretary determines that to do so would promote sound community development. All or part of the housing portion of a public purpose project shall be occupied by families of limited income. At the request of a political subdivision, the Secretary may designate a distressed area of the political subdivision after considering factors including: the availability, cost, and condition of housing and neighborhood facilities, including the age and number of abandoned and substandard structures; the incomes of residents relative to State or area-wide regional median incomes, including the number of individuals who are welfare recipients, unemployed, or living in poverty; the need to finance housing or public or private facilities to upgrade the social and economic conditions of the distressed area; the plans and financial commitment of the political subdivision to undertake improvements in the distressed area; and other standards and criteria that the Secretary considers relevant, including standards established for other State or federal programs.