Debunking the common laissez-faire myth surrounding turn-of-the-century American foreign relations allows for a reconceptualisation of American imperialism from 1890 to 1913. The Republican Party, the party of protectionism, found itself riven by internal disagreements over the future of the protectionist system and US imperial expansion. From within Republican protectionist ranks arose a progressive wing that increasingly looked beyond the home market for the country’s growing American agricultural and manufacturing surpluses. They did so against staunch anti-imperial opposition not only from American free-trade independents, but also from the Republican Party’s isolationist home-market protectionists, who yet feared or disdained foreign markets and colonial acquisitions. These progressive Republican proponents of empire combined coercive trade reciprocity with protectionism—an expansive closed door—and worked hard to extend American imperial power through informal means of high tariff walls, closed US-controlled markets, and retaliatory reciprocity if possible, by formal annexation and military interventionism when necessary. The American Empire thus arose owing to the imperialism of economic nationalism, not the imperialism of free trade.