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The recent occurrence of large fires with a substantial stand-replacing component in the southwestern United States (e.g., Cerro Grande, 2000; Rodeo-Chedeski, 2002; Aspen, 2003; Horseshoe 2, Las Conchas, and Wallow, 2011) has raised questions about the historical role of stand-replacing fire in the region. We reconstructed fire dates and stand-replacing fire patch sizes using four lines of tree-ring evidence at four upper montane forest sites (>2600 m) in the Madrean Sky Islands and Mogollon Plateau of Arizona and New Mexico, USA. The four lines of tree-ring evidence include: (1) quaking aspen (Populus tremuloides) and spruce-fir age structure, (2) conifer death dates, (3) traumatic resin ducts and ring-width changes, and (4) conifer fire scars. Pre-1905 fire regimes in the upper montane forest sites were variable, with drier, south-facing portions of some sites recording frequent, low-severity fire (mean …