At 145,388 square miles—93 million acres—Montana is a big state. Were the state’s 902,195

residents spread evenly across the land, there would only be six persons per square mile. Of

course, people are not scattered uniformly. Sixty percent live in just seven of the 56 counties.

Thirty-six percent live in eight cities. Six of the seven most populous counties and six of the

eight largest cities are located in western Montana where recent growth has been rapid. This

concentration of population leaves much of the state with a very low population density.

Almost a third of Montana is owned by the state and federal government: 17 million acres

managed by the U.S. Forest Service, mostly in the western half of the state; 8 million acres

administered by the Bureau of Land Management and lesser acreage controlled by the National

Park Service and other agencies. The state owns more than six million acres, most of it managed

by the Department of Natural Resources. There are seven Indian reservations totaling 2.5

million acres. Agriculture, recreation and tourism, forest products, and mining form the base of

Montana’s economy. The eastern third of Montana is prairie land, part of the Northern Great

Plains ecosystem. The middle third is prairie surrounding island mountain ranges. Western

Montana is characterized by rugged mountain ranges and deep river valleys. Generally speaking,

precipitation decreases from west to east and varies from 80 inches in the high western

mountains to less than 10 inches in the northeastern plains.

Montana has been called the “Headwaters of the Continent.” It is the only state that sends water

to three oceans. The state is comprised of three major and two minor river basins:

• • Two tributaries of the Columbia, the Clark Fork and the Kootenai, drain 26 million acre

feet from 25,125 square miles. This basin is just 17 percent of the land area but accounts for 53

percent of the state’s annual surface flow.

• • Conversely, the Missouri and its tributaries drain 56 percent of the state, over 82,000

square miles, yet only carries 17 percent of the annual surface flow (8 million acre feet).

• • The Yellowstone drains 36,000 square miles (24 % of the state) and carries 9.5 million acre

feet (21%) to meet the Missouri just inside the North Dakota border.

• • The Little Missouri River slips through the southeast corner of the state draining just two

percent of the land area in Montana.

• • The St. Mary’s River flows north toward the Arctic Ocean from Glacier National Park,

draining two percent of the water from one percent of the land.