This chapter discusses the data and methods used by the US National Park Service to estimate the economic effects of National Park visitor spending to local and regional economies. Topics covered include a summary of economic effects analyses, required data for analysis (visitor count data, trip characteristics and spending patterns, and regional economic multipliers) and how these data are combined to estimate visitor spending and economic effects. The chapter includes an applied example for Yosemite National Park and shows how park-level data can be combined to estimate and showcase state- and national-level visitor spending effects.