MINOT (AP) - A favorable monetary exchange rate for Canadians and increased activity in North Dakota's oil patch appear to be boosting airline passenger numbers at airports in this city, Williston and Dickinson.

The boom in boardings is prompting airport officials in Dickinson to expand the parking lot there.

Passenger boardings at the Minot airport in February were up 21 percent from the previous year, according to the North Dakota Aeronautics Commission. Airport manager Patrick Dame estimated that as many as half of the cars in the parking lot recently have had Canadian license plates.

Neal Watkins of Swan Lake, Manitoba, drove his family the five hours to Minot to catch a flight to London recently.

"We were going to go (fly out of) Winnipeg until we checked down here and it was a little cheaper," he said.

February boardings at Williston were up 31 percent over the year. Dave Skalsky, owner of a local car rental agency, said his business has picked up with about five extra rentals a week. He attributes the increase largely to oil company officials who fly in.

Dickinson's boardings were up 34 percent, and airport authority officials said increased oil activity in western North Dakota was a big reason.

With passenger boardings at a 10-year high, "We had about 15 to 20 cars parked on the grass at any given time," airport manager Matt Remynse said.

The overflowing lot has led to not just ruts and dead grass but also drivers using the wrong exits, motorists driving across ditches, and parked vehicles blocking the traffic flow, Remynse said. Officials plan to add 30 more parking spaces this summer.