Elder Grove School is asking school district voters to approve a $5 million bond to expand the school.
Voters have until Dec. 11 to complete their mail ballots, which were sent out by the Yellowstone County Elections Office.
If voters approve the bond, the school would build to accommodate its growing population.
"In the last few years, we've been experiencing a lot of growth," said Justin Klebe, school principal and superintendent. "The reasoning is that we're just out of room."
The school, which is west of Billings and covers about 62 square miles all the way to Molt, had 427 students as of Monday, an increase of 12.5 percent from the 2011-2012 school year.
The ballot says the school addition would "include classrooms, a library and computer lab; adding a parking lot; related improvements; and paying costs associated with the sale and issuance of such bonds."
Klebe said the school has had to add a new classroom each of the past four years to keep up with the student population and that the school is now out of room.
If the construction bond passes, the school would put one more classroom in its current computer lab, and then switch to a mobile lab while the construction takes place.
Klebe said construction would probably begin in spring 2014.
If the bond fails, Klebe described two scenarios of where the school could go. The first would involve sending Elder Grove seventh- and eight-graders to Elysian School, which plans to run its own bond in February.
"We have to do something with the kids," Klebe said. "If we don't have any place to put them, we have to find someplace to put them."
That option would cost county taxpayers a total of about $1,088 per student, he said.
In the second scenario, the school would bring in temporary modular units for the extra students, which could offer a temporary solution.
"We'd bring them in in hopes of running a bond in the future," Klebe said. "If it continually gets knocked down, the students in seventh and eighth grade would still have to go eventually."
He said the growth in the district is due to several factors, including Billings' natural westward expansion, families from North Dakota's Bakken oil boom and businesses supporting the boom setting up shop in the Billings area.
Interest rates, Klebe said, make the bond proposal more viable, with "interest rates at an all-time low," which would also allow to school to refinance other bonds to save money.
Bret Rutherford, Yellowstone County elections administrator, said this year's presidential election increased the number of registered voters in the school district to 1,903, meaning more people could potentially vote on the bond.
As of Tuesday, 757 of the ballots had been returned.
"That's about 40 percent so far, which is good for a vote like this," Rutherford said. "My fear was that people would say there was an election last month and not even look at this. But that hasn't been the case."
Several past levies — including one earlier this year — have failed at Elder Grove, but Klebe said it's important for as many people in the district as possible to vote.
"I encourage everybody to vote, regardless of what their vote is," he said.