ATLAS OF UNITED STATES TREES 
VOLUME 3. MINOR WESTERN HARDWOODS 
INTRODUCTION 
This volume is the third of an Atlas with large maps showing 
the natural distribution or range of the native tree species of 
continental United States. “Atlas of United States Trees, 
Volume 1, Conifers and Important Hardwoods” (Little 1971) 
has an introduction to the series, which may be condensed and 
adapted here. The present project is to be completed by 1976 in 
five volumes. However, additional volumes on special subjects 
and revisions may be prepared later, as needed. 
Maps demonstrate clearly and graphically where the trees 
grow wild better than written summaries and have many 
obvious uses. Assembled in atlas form for ready reference, 
these distribution maps are available to foresters, botanists, and 
all others interested in trees for use without restriction, since 
U.S. Government publications are not copyrighted. Users will 
render a service toward the improvement of the maps by 
reporting errors and range extensions. Review and correction is 
desired for a later, revised edition. The ultimate aim is to 
produce a set of highly accurate maps of wide acceptance. 
The native tree species are not distributed across the United 
States at random, nor are they dispersed equally by States. 
However, some tend to occur in similar patterns related to 
climate and other factors. A brief summary of the contents 
follows. All volumes except the first are limited and arranged 
geographically. 
Volume 1 contains maps of 200 native tree species, all the 
native conifers or softwoods, including the needleleaf and cone- 
bearing evergreens (94 species, also 2 shrub species) and the 
important hardwoods (106 species). Coverage is partly botanical 
and partly practical. Nearly all trees now important commer- 
cially for lumber are represented. Occurrence in Alaska is 
shown on maps of North America. 
Volume 2, “Alaska Trees and Common Shrubs” (Viereck and 
Little 1975) has maps of Alaska for 82 native species, including 
32 of trees, 6 of shrubs rarely reaching tree size, and 44 more of 
common shrubs. This special volume was needed because the 
northernmost and largest State is geographically separated from 
the others. It follows and supplements also “Alaska Trees and 
Shrubs” (Viereck and Little 1972). That handbook, primarily for 
identification, has descriptions, drawings, small maps, and 
additional information for 128 species, including the remaining 
shrubs. Occurrence outside Alaska is shown on North American 
maps in Volumes | and 3. 
Volume 3, “Minor Western Hardwoods,” contains maps of 
210 tree species native in western contiguous (or conterminous) 
1 Names and dates in parentheses refer to Selected References, p. 11. 
United States but not in Volume 1. The area covered includes 
all 11 far western contiguous States, Washington, Idaho, 
Montana, Oregon, California, Nevada, Utah, Wyoming, Colo- 
rado, Arizona, and New Mexico, also Trans-Pecos Texas (the 
southwestern part west of the Pecos River; base map 2—SW). 
Coverage extends eastward for those westerm species also in the 
row of six Midwestern States of North Dakota, South Dakota, 
Nebraska, Kansas, Oklahoma, and Texas. Thus, ranges are 
charted in 17 States. Also, occurrence of 15 species in Alaska is 
shown on maps of North America. 
Volume 4, ‘Minor Eastern Hardwoods,” will contain maps of 
about 170 tree species native in eastern contiguous United 
States not in previous volumes. The area covered extends west 
to include the row of six Midwestern States of North Dakota, 
South Dakota, Nebraska, Kansas, Oklahoma, and Texas. 
However, the tropical trees of southern Florida will be omitted. 
Also, the genus of hawthorns (Crataegus) has been left out 
because of taxonomic difficulties. 
Volume 5, “Florida Trees,” will have maps of about 100 
species of tropical trees confined mostly to the southern part of 
that State. Also to be included are maps of the remaining tree 
species native in Florida, adapted from those in Volumes | and 
4. 
Another Forest Service publication, “The Distribution of 
Forest Trees in California” by James R. Griffin and William B. 
Critchfield (1972) has detailed maps of 86 species of that State, 
including the conifers and commercially important hardwoods 
and most other large trees. Those maps were begun some years 
earlier by the Vegetation Type Map (VTM) survey of California. 
Most of those species were mapped earlier in Volume 1 but with 
less detail in California. In Volume 3 the California ranges of 15 
species are from that source. However, this Atlas volume has 
maps of about 85 additional tree species of that State, mostly of 
small size or shrubby. 
The native tropical trees of Hawaii and the Commonwealth of 
Puerto Rico are best treated separately. Maps of 100 species in 
Puerto Rico based on a forest survey were published in 
“Common Trees of Puerto Rico and the Virgin Islands” (Little 
and Wadsworth 1964). 
HISTORY OF TREE DISTRIBUTION 
MAPS 
The history of tree distribution maps in the United States has 
been reported in Volume 1, while early work by the Forest 
Service has been reviewed by Little (1951). George B. Sud- 
worth, first dendrologist of the USDA Forest Service, began 
work with the Bureau of Forestry in 1886. Tree ranges were 
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