Idaho’s population growth – and the shifts toward more urban areas over the last several decades – has had differing effects on the population density in the 44 counties, and as density increases that generally impacts services. It can drive up the cost of living and adversely affect water and air quality and wildlife but increase community vibrancy and amenities.

The 1950 census found Canyon County with the highest density in the state. Neighboring Ada County was a distant second with 36 percent fewer people per square mile. While Canyon County is half the size of Ada County, it picked up residents as Ada County saw real estate prices escalate and open spaces decrease.

At the other end, Payette County is the state’s smallest and one of its densest. With its comparatively small towns clustered near the interstate, Payette’s density is the result of location near the Oregon border and the Boise metropolitan area. Ontario, Ore., just over the border, attracts many Idaho workers because of its higher minimum wage – $9.10 an hour versus Idaho’s $7.25 – that drives up wages above the minimum as well.

Teton saw the greatest increase in density from 1980 to 2013, spurred by its location close to Jackson Hole, Wyo., where many residents commute, and by technological advances that allow people to work remotely from a place of scenic beauty. Density rose 250 percent over 33 years. Seasonal tourism with its influx of workers and visitors or part-time residents causes population to fluctuate in Teton County. But there is stability because of access to the Jackson ski area in winter and to Grand Teton and Yellowstone national parks.

Madison County, where the Church of Jesus Christ of Latter-day Saints has had an institution of higher education for over a century, saw dramatic growth when two-year Ricks College became Brigham Young University-Idaho in 2001. Density has nearly doubled since, prompting a construction boom of apartment complexes. Today, the state’s third smallest county in area is its fourth densest in population.

For Nez Perce County, the experience since 1950 has been different. While the county and the Lewiston metro area have been growing, others have outpaced that growth, dropping Nez Perce from fifth densest in 1950 to eighth in 2013.

Bonneville County has steadily increased in density as its economy and jobs have continued expanding, anchored by the Idaho National Laboratory.

While the densities of the state’s largest counties have increased four to six times since 1950, the density in Twin Falls County, which underpins the south central economy, increased just 50 percent.

Kootenai County’s increase in density has been the most consistent over the past 63 years. Its scenic beauty – and the recreational amenities developed over the past 30 years – has attracted visitors who became residents or second-home owners.

Unlike Ada and Madison counties with their universities, Latah County and the University of Idaho have not experienced that magnitude of population growth, causing it to slip comparatively in density. It is also isolated geographically so it does not benefit from any population growth in nearby areas.

The least dense counties have essentially remained the same since 1950. Blaine and Boise counties have been replaced by Clearwater and Adams counties. Blaine has seen growth because of the world renowned Sun Valley resort while Boise County has grown as a bedroom community for Ada County. After a surge in population during the housing boom of the 1960s and 1970s, Clearwater County has essentially stagnated with its population falling back to levels approaching 1950. Adams County, which also has a resource-reliant economy, experienced a surge during the mid-2000s with activity on the Tamarack Resort in neighboring Valley County. But when the resort went under, economic activity subsided in both Adams and Valley counties.

Clearly density can be affected by many factors. Weather patterns, changes in the road infrastructure, geographic seclusion and bouts of job creation, such as North Dakota has been experiencing, affect growth or the lack of it. While increasing density has pluses and minuses, it is generally better than the stagnation that results when counties lose a major industry or are bypassed by rerouted highways.

Jan.Roeser@labor.idaho.gov, regional economist
(208) 735-2500 ext. 3639