This chapter examines the process of market-building on the western frontier, focusing in particular on the process through which the expansion of the railroad network in the late 19th century linked towns to the grain buyers who owned and operated the elevators used to load grain on to railcars. It begins by describing western market-building as part of a larger transcontinental project designed to link the agrarian periphery to existing urban centers, leading to the creation of a vast market network. Rail lines played a unique role in this context, serving as a venue for the creation of distinct market communities defined by the relationship between towns and elevator owners. Using formal network analysis, it is shown that market communities differed in terms of not only in terms of their size and geographic structure, but in the centrality of the elevator owners with which the lines partnered.