Means, standard deviations, and quartiles of fuel loadings were determined for litter, for downed woody material of 0 to one-fourth inch, one-fourth to 1 inch, 0 to 1 inch, and 1 to 3 inches, for herbaceous vegetation, and for shrubs by cover types and fire groups. The studies were conducted at four locations in northwestern Wyoming, western Montana, and northern Idaho. Most distributions were strongly skewed to the right. Ratios of medians-to-means for the fuel components by vegetation type and location all averaged close to 0.6 except for shrubs, which averaged 0.18. Correlation coefficients for fuel component pairs were mostly less than 0.30. Fuel loadings and predicted fire behavior varied considerably within cover types and fire groups compared to between vegetation types. Results suggest that a few models of physical fuel properties for rating fire danger and predicting fire behavior by broad vegetation types are appropriate for practical applications. Other implications to predicting fire behavior using mathematical models are discussed.