This dissertation explores how people transform “new” and unfamiliar environments through colonization. While adaptationist perspectives typically stress how the environment shapes human behavior and communities, I integrate historical ecology and settlement ecology to examine how people mold, maintain, and manage landscapes. Rather than passive backdrops, landscapes are dynamic, produced as humans actively modify the environment. Boundaries, whether stable or fluid, divide and structure landscapes. As a type of boundary, frontiers can be understood as centers of social interaction and exchange, but more often are viewed as peripheries, remote but ripe for settlement, or wild zones where pioneers struggled to survive. Given factors like severe winters, poor soils, and warfare, the latter portrayal dominates narratives of America’s Eastern frontier during the 18th and 19th centuries. To interrogate notions of a largely static, intractable frontier environment, I assess how Euroamericans transformed the Downeast Maine region through settlement and enclosure. To determine how they colonized, cleared, bounded, and cultivated the landscape, I analyze archival, archaeological, and geospatial data from nine towns. First, I trace changes in the landscape and agricultural production between 1792 and 1811 using historical tax valuations. Statistical and geospatial analyses of this data suggest some town landscapes were more thoroughly improved and refined through agriculture than others. Initial parallels between frontier agricultural production and that of southern New England challenge notions of the intractable frontier environment. Second, I juxtapose 18th- and 19th-century maps with Google Earth and Light Detection and Ranging imagery to explore how the frontier landscape was settled, divided, and enclosed. By identifying historical landscape features that endure in the modern landscape, I chart continuity and change in the structure of these towns through the present. Finally, I examine the Foster Farmstead in Deer Isle, Maine as a case study to investigate how settlement and agrarian activities became physically embedded in the landscape at a small scale. My archaeological survey and excavation reveal settlement and landscape features like foundations, stone walls, and stone piles, which attest to how descendants of the Fosters continued to inhabit, transform, and enclose the land through time.