Minnesota school bus companies are offering a signing bonus of up to $1,000 and $16-an-hour starting salaries as they face one of the worst driver shortages in recent years.

Companies are poaching drivers from one another and peppering the Internet with classified advertisements and still remain woefully understaffed in the beginning weeks of the school year. At Beacon Academy Charter School in Maple Grove, buses were two hours late and parents had to organize a carpool to get students home. To ease the problem, the bus company’s staffers were forced to drive routes.

“Everybody’s a bus driver,” said Kevin Bisek, general manager of American Student Transportation, which is still 20 drivers short.

The driver shortage is hitting school buses across the country, spurred by an uptick in the economy and an intensely competitive market for drivers.

A 2015 survey completed by the magazine School Bus Fleet found that only 6 percent of school bus contracting companies nationally said they have enough drivers, compared to 15 percent without a shortage in 2014. A sizable share, 28 percent of respondents, said they have a severe or desperate shortage of school bus drivers.

The problem is showing up statewide in Minnesota.

Troy Voigt’s School Bus Transportation in St. Cloud is a smaller company and needs six more drivers; in the meantime, it is pinched to cover all its routes.

School districts that have their own buses and hire their own drivers are seeing shortages too, said Thomas McMahon, executive editor at School Bus Fleet.

Beacon Academy has been struggling to adequately transport children since school started, when the shortage required some of its 250 bus riders to carpool home. Other buses got home two hours after school let out on the first day of classes.

Parents organized a carpool effort as teachers stayed after school to supervise students who were waiting for late buses.

“No buses arrived” on the first day of school, said Doug Harrison, parent of two Beacon Academy students. “Then we found out after the fact that there was this big issue.”

By Wednesday, a full week after school started, things still weren’t back to normal, said Beacon Academy Principal Sean Koster. The school has contracted with another company to have more buses showing up at dismissal time.

Nationally, the driver shortage has been a persistent problem, to some degree, for the last 20 years, said Ronna Weber, executive director of the National School Transportation Association.

When the economy is strong and unemployment is low, potential bus drivers might balk at the qualifications for the job, she said. In Minnesota, school bus drivers must hold a commercial driver’s license, pass a criminal-background check, a driver history check, a drug test and a physical exam.

In addition, drivers typically earn low pay and the work can be intimidating, McMahon said.

“You’re driving a 40-foot bus with a few dozen kids,” he said. “That’s a big responsibility.”

The companies have been upping their incentives, offering bonuses and higher salaries to find new drivers and lure more experienced ones from other companies, McMahon said.

American Student Transportation and First Student offer a $1,000 signing bonus. Voigt’s starting bonus is $700.

First Student training center manager Brian Miller said drivers’ hopping from company to company is “pretty normal practice in business.”

The classified ads are eye-catching and offer flexible routes in nearly every corner of the Twin Cities. One read: “$16.00 an hour starting, NO experience necessary! Up to $18.50 for professionals with experience.” Some of the ads tout that the jobs are great for retirees, college students or anyone looking to work two to six hours a day.

The shortage is particularly hard on smaller school districts and for the state’s growing number of charter schools.

“The company can’t take care of the little schools anymore because there just aren’t enough drivers to go around,” Voigt said.

Bisek said his company is trying to fill its driver’s seats, but competition from other employers is intense and they still need to ensure that drivers meet high standards.

“You’re hauling around children,” Bisek said. “They’re our most prized possession, and the bottom line is, we do have a high criteria that needs to be met.”