SANDUSKY, Mich. — The Cessna airplane touched down about midnight, dropped a load of drugs and was back in the air in 90 seconds. Suddenly, the pilot of a U.S. border patrol helicopter hovering nearby turned on a powerful spotlight and tracked an SUV fleeing with hockey bags stuffed with 175 pounds of marijuana and 400,000 Ecstasy-type pills.

The bust by federal agents didn’t happen on the Southwestern border. It was in Michigan’s rural Thumb region next to a soybean field. The remote Sandusky airport offers a smooth runway at any hour to anyone who needs it, a perfect landing for drug smugglers who can cross the Great Lakes from Canada in minutes.

Beefed-up enforcement along the Mexican border has made smuggling more challenging for criminal cartels using the major southern routes, but drugs continue to flow across the porous northern border through airstrips like this one as officials look for new ways to fight back.

Tracking rogue planes at low altitude with their transponders off is “like trying to pick a needle out of a haystack,” said John Beutlich of U.S. Customs and Border Protection, who oversees air and marine operations from Washington state to Maine.

Tiny airports feel helpless.

“Shoot, we’re just a big cherry to pick and didn’t realize it,” said Joe Allen, manager of the Sandusky airport, 90 miles northeast of Detroit.

He installed a fence to keep cars from meeting planes at the runway, but the property isn’t staffed at night. Border agents could offer just two signs asking people to call an 800 number if they see something unusual.

Homeland Security Secretary Janet Napolitano says the U.S. hopes to start tapping into 22 Canadian radars to fill surveillance gaps on the border. Officials say the U.S. has one national radar network made up of feeds from the Federal Aviation Administration and the Defense Department.

Border authorities also conduct routine air patrols, but some lawmakers would like military-grade radar along with drones that could detect small aircraft.

“All everybody wants to talk about are drug cartels coming across the southern border. I don’t mean to diminish that but the northern border has gotten very little attention up until recently,” said U.S. Rep. Candice Miller, R-Mich., a senior member of the House Homeland Security Committee.

A new law requires the Obama administration to come up with an anti-drug strategy on the U.S.-Canada border by summer.

Canada is a significant source of high-quality marijuana and the amphetamine Ecstasy. More than 2 million doses of Ecstasy were seized on the northern border in 2009 compared to just 312,000 in 2004, the Drug Enforcement Administration said.

Most shipments come by road. But the 2009 flight from Ontario to Michigan, the subject of a recent federal trial, provided insight into drug operations that use small planes. Officials don’t know how frequent such flights are but consider the vulnerability alarming.

The Sandusky airport has spent $2,000 on cameras and hopes to install more.

“We’re outside radar,” Allen, the manager, said, running his finger over a map of Michigan’s Thumb. “You can come and go as you please. You don’t even have to file a flight plan.”

The minimal help he received from authorities — the warning signs — had to be fixed before he posted them: They referred to suspicious boats, not planes.

Beutlich, the senior Customs and Border Protection official, said his agency’s routine air patrols “can’t be everywhere.”

“I don’t think there is more than just vigilance,” he said, adding that law-abiding users of small airports typically are the best sources to report trouble.