COEUR d'ALENE — When it comes to economic growth over the last four years, Kootenai County is almost No. 1 in Idaho.

According to a new study conducted by financial technology company SmartAsset, Kootenai County ranks second among all Idaho counties when it comes to overall GDP, or gross domestic product, growth over the last three years. Only Ada County ranked higher in GDP growth, which Regional Economist Samuel Wolkenhauer said is a measurement used to gauge all of the economic action in a given place.

"What's interesting to me is the official measurers of GDP, the U.S. Bureau of Economic Analysis, do not do county-level estimates," Wolkenhauer said of the study. "So I am kind of curious to know where they got these numbers from. With that being said, it's a very plausible number."

The SmartAsset study states that Ada County saw $832 million in GDP growth since 2013, while Kootenai County saw $290 million. Wolkenhauer said GDP is traditionally calculated for states and sometimes larger metropolitan areas, and looks at a few aspects like consumption, investment, and government spending.

Those aspects, he added, make getting GDP data for counties a challenge. In his work as an economist with the Idaho Department of Labor, Wolkenhauer said they use the measurement of total wages and salaries paid in a given year because, like GDP, it is representative of all economic activity.

Last year, Kootenai County was second in the state for increases in total wages and salaries, Wolkenhauer said. That equates to a $111 million increase.

Wolkenhauer added that the data his department uses measures the other side of the coin when compared to GDP. But, the economic outlook results are the same regardless of what statistic is used.

"From both sides, and even in our long-term projections, we are forecasting that Kootenai County will see the second highest growth in the state," he said. "I don't know exactly how they got the GDP numbers, but it seems pretty reasonable and we are certainly in agreement on the rankings."