Final answer:
The most crucial element in successful efforts to improve existing housing in inner cities is the involvement of local citizens and community leaders, as programs that stimulate community engagement tend to have the most sustainable impacts.
Step-by-step explanation:
The experience of programs such as the American Council to Improve Our Neighborhoods and Habitat for Humanity indicates that the most important factor in the success of efforts to improve existing housing in inner cities is E. Involvement of local citizens and community leaders. These grassroots initiatives often rely on the participation and investment of those who live in the communities being serviced. Programs offering tax breaks for renovations or selling city-owned houses for a nominal fee, contingent on residency and upkeep, have made significant impacts. Such approaches emphasize local engagement over more impersonal solutions like modification of zoning ordinances, federal funds, union support, or credit ease for loans. Ultimately, it's the commitment of residents to improve their own neighborhoods that drives sustainable community development and renewal.