Cooperation when N is large: Evidence from the mining camps of the American West

The sources of cooperation in small groups are well documented. There is, however, less understanding about cooperation in large groups. I study the enforcement of property rights in the mining camps of the American West. Miners demanded secure property rights and protection from violence to exploit the region's mineral wealth. In the model, miners must divide their labor between mining and supporting property rights institutions. The main prediction of the model is that cooperation in property rights enforcement emerges only when social norms of cooperation are sufficiently widespread. The model also predicts that social norms are less effective in mining camps with large populations or high labor productivity. I test these predictions against detailed evidence from the letters, diaries, and reminiscences of miners in 25 camps in California, Colorado, and Montana and find that the evidence supports the predictions. The results show that social norms can significantly lower the costs of collective action in large groups.