6 Miscellaneous Circular 19, U. S. Dept. of Agriculture. 
miscellaneous unlisted causes, 2 per cent from incendiarism, and 1 
per cent from the carelessness of lumbermen. 
Lightning fires are not distributed evenly over all the intermoun- 
tain region. Figure 4 shows the percentage of fires caused by light- 
ning in the different parts of this region. ‘In western Idaho light- 
ning-caused fires are most frequent, forming 62 per cent of all the 
fires. In eastern Idaho lightning causes only 21 per cent of the fires. 
In the high mountains of western Wyoming about one-third, in 
f 
NEVADA 
é 4 
Be 
Forest Fires Due ( 
To LIGHTNING i 
IN DIFFERENT PARTS 
OF THE 
INTERMOUNTAIN REGION 
Fig. 4. 
Utah about one-fourth, and in Nevada about one-tenth of the fires are 
due to lightning. 
Compare hghtning with the careless camper as a cause of forest 
fires. In southeastern Idaho campers are responsible for about three 
‘imes as many fires as hghtning, and in Nevada for nearly four times 
as many. In western Wyoming nearly two-thirds of all fires are 
caused by campers and only about one-third by lightning. It is only 
, 
in the forests of western Idaho that lightning is more active than 
