As the suburban landscape developed during the 20th century and the outer city became a refuge for the wealthy and, later, the burgeoning middle class, sociologists and urban geographers such as Harvey Molotch, David Harvey and Neil Smith began to study the structure and revitalization of the most impoverished areas of the inner city. In their research, impoverished neighborhoods, which often rely on tightly knit local ties for economic and social support, were found to be targeted by developers for gentrification which displaced residents living within these communities. Political experimentation in providing these residents with semi-permanent housing and structural support – ranging from Section 8 housing to Community Development Block Grant programs- have in many cases eased the transition of low-income residents into stable housing and employment. Yet research covering the social impact of forced movement among these residents has noted the difficulties individuals often have with maintaining a level of economic comfort, which is spurred by rising land values and inter-urban competition between cities in as a means to attract capital investment. The interaction between inner-city dwellers and middle class passersby in such settings has also been a topic of study for urban sociologists.