The American mobile home is a paradox; though prefabricated mobile homes are, in theory, designed for continued transportability, in practice, the vast majority of mobile homes in the United States are tethered to and bound by a specific plot of land. Integral to the process by which the mobile home becomes embedded in land is the act of mobile home improvement; additions and upgrades, both prefabricated and self-built, only serve to further settle the home in a specific locality. This thesis seeks to investigate the physical nature of mobile home improvements and their relation to regulatory environments, particularly land regulation, through a study of select mobile home parks located in the greater Knoxville, Tennessee, region of the United States. Drawing on evidence from site observation, interviews, and critical mapping, I demonstrate that select forms of upgrading in specific Appalachian mobile home parks are incremental in nature. Furthermore, I argue that these forms of upgrading are physical manifestations of informality that serve to “fix” mobile homes to specific sites. This informality, as will be established, is enabled and abetted by the regulatory landscape in which the upgrading occurs. Through this research, I seek to systematize a specific instance of informality in the built environment of the United States through an analysis of its physical manifestations and the encompassing structures that enable its occurrence.