This paper describes statistical evidence supporting the theory that early modern frontier mining towns in Mexico had more unstable economies than central agricultural towns. Series of sales tax revenues are used as a proxy for economic activity in the towns of Zacatecas and Guadalajara during the period of 1578-1669. A description of the analysis of variance will be presented, and differences in volatility patterns will be highlighted. Further, volatility will be placed within the context of the rate of discount paid by miners to exchange bullion for coins
