Idaho K-12 enrollment passed a milestone this fall.

For the first time, more than 300,000 students attended the state’s public schools.

The new numbers reinforced an old trend in Idaho demographics. Most of the growth occurred in urban areas.

First, the bottom line

Fall enrollment came in at 300,422, according to State Department of Education reports. That’s up 4,938 from 2015 — translating to a 1.7 percent increase. (Click here to download the numbers for your local district or charter school.)

Let’s put that enrollment increase into a budget context.

In March, lawmakers approved a series of budgets boosting K-12 spending by 7.4 percent. This increase would appear to keep up with enrollment growth and the one-year inflation rate — which, according to the Consumer Price Index, is about 2 percent.

But one Washington, D.C.-based group isn’t sold. In a report issued earlier this month, the Center on Budget and Policy Priorities asserted that Idaho is among 19 states with a K-12 budget that failed to keep pace with enrollment growth and inflation.

The largest of them all

No debate here. And no surprise either.

The West Ada School District remained Idaho’s largest district, and by a long shot. Fall enrollment came in at 38,164, buoyed by an increase of 685 students.

Put another way, that one-year increase eclipses the total enrollment in 95 of the state’s 167 districts and charter schools.

Enrollment increases are nothing new in this suburban district, which has experienced growth in good times and bad.

The smallest of the small

That title goes to the Prairie elementary school district in Elmore County — and to the Prairie district alone.

Prairie’s fall enrollment came in at seven students, although this represents an increase from six students a year ago.

Across the state, North Idaho’s Avery School District also had six students in 2015. But Avery experienced a growth spurt of sorts; its 2016 enrollment came in at 11.

Urban growth areas

Idaho’s growth is anything but uniform. And the 2016 enrollment numbers pretty much confirmed that.

Five districts and two charter schools account for more than half of the state’s enrollment growth. And all of these districts and charters sit in or near Idaho’s urban areas: the West Ada, Boise, Bonneville, Vallivue and Twin Falls districts; the Nampa-based Idaho Arts Charter School; and Alturas Academy, a new K-6 charter school in Idaho Falls, which opened its doors to 269 students this fall.

Paying for sudden growth

There’s another bottom-line impact, at least when it comes to growing school districts. When districts report an enrollment increase in the first few days of the new school year, their trustees can vote to collect an emergency property tax levy to help cover this growth.

West Ada, Bonneville and Twin Falls will collect more than $6 million in emergency levies this year. Boise and Vallivue decided not to collect an emergency levy. (Click here to get a rundown on emergency levies across the state.)

And where the numbers dropped

The Nampa School District sustained the biggest enrollment decrease in Idaho, a dropoff of 474 students.

At least the decrease wasn’t a surprise. District officials expected a decline in grade school enrollment — due to the expansion at the Idaho Arts Charter School and the launch of another new charter school, Gem Prep, serving kindergarten through fourth grade. And Nampa district officials set their budget accordingly, bracing for a decrease in state funding.

(Still, it’s important to remember that state K-12 funding isn’t tied to enrollment. Instead, the state carves up its dollars based on another calculation, known as average daily attendance.)

Among the other notable dropoffs: the Idaho Virtual Academy, the state’s largest charter school, reported an enrollment decrease from 2,182 to 1,992. This continues a steady and significant decline in IDVA’s numbers, and is consistent with an overall enrollment decline in online schools.

Advocates for charter and virtual schools say schools such as IDVA cater to at-risk students who leave traditional schools for any number of reasons. Consequently, these schools pick up enrollment over the course of the year.