Frontier Seaport begins by asking: when, how, to what degree, and with what consequences did “frontier” and “Atlantic” coexist in early Detroit? In six chapters, it argues that colonial Detroit's status as a successful fur-trading center, accessible via the Great Lakes, hastened the town's economic and cultural incorporation into the broader Atlantic world. Early chapters foreground Detroit's Atlantic connections, showing how they were strengthened by the settlement's positioning on the frontier. In turn, by 1780, almost 80 years after its founding by the French, British Detroit participated fully in the types of reciprocal, transoceanic commerce that characterized other North Atlantic settlements. Although economic and cultural inclusion came quickly, political incorporation took a slower and fickler course. The town's close proximity to Native groups, its physical separation from indifferent imperial powers, and repeated political upheavals made Detroiters resistant to complete assimilation into the broader Atlantic world. These are the subjects of later chapters, which foreground Detroit's frontier connections and localisms, establishing that they were created, strengthened, and ultimately eroded by its Atlantic associations. By the time of Michigan's U.S. statehood in 1837, Detroit's residual distinctiveness had waned, rendering the town reminiscent of any other American metropolis. In short, Frontier Seaport demonstrates that between 1701 and 1837, Detroit was a complicated geographic space as much tied to “empire” as to “frontier,” and as committed to attaining its own economic, political, and cultural prowess as it was to functioning in more traditionally colonial ways.