Southbound border traffic into Whatcom County has returned to levels last seen before the Sept. 11, 2001, terrorist attacks.

Last year 15.4 million people crossed the Canada/U.S. border into Whatcom County, an 8.5 percent increase compared to 2011. It's the highest annual total since 1997, when 18.3 million came into Whatcom County, according to data collected by Western Washington University's Center for Economics and Business Research.

While many Whatcom County residents have noticed the increase in Canadian shoppers at retail stores and travelers at the Bellingham airport, it's also been business people making investments in the community, said Jim Pettinger, president of International Market Access in Ferndale. His business offers a variety of cross-border services to help with sales and distribution.

"We really see that (increase in business people traveling into Whatcom County) with our business," Pettinger said. "British Columbia businesses are getting stronger every day, and they are looking at the U.S. market (to expand)."

Border traffic is expected to increase in 2013, but not as fast as recent years because there's been little change lately in key economic factors, such as the Canadian dollar and product prices.

Hart Hodges, director at Western's CEBR, said the difference in price on a variety of items, including gasoline and dairy products, remains large enough to make the trip attractive, even if the Canadian dollar were to weaken slightly. The Canadian dollar has remained at around parity with the U.S. dollar for the past three years.

He doesn't expect the traffic to get back to the levels like 1990, when 27.9 million people crossed the border going south. One reason is because more U.S. stores are in the lower British Columbia mainland than 23 years ago. Also, while getting across the border is easier than the first several years after 2001, it is still more difficult than 1990.

Ken Oplinger, president of the Bellingham/Whatcom Chamber of Commerce & Industry, also said border traffic won't return to 1990 levels in the coming years. But he thinks the recent improvements at the border with infrastructure and staffing levels will lead to more traffic in 2013, benefiting the northern communities in Whatcom County.

"(Canadians) are seeing the border more as a way to make quick trips to get gas, and that should benefit communities like Blaine and Sumas," Oplinger said.

Pettinger said the 2010 Winter Olympics in Vancouver turned out to be well-timed in terms of helping Whatcom County's economy. Significant construction work was done on the nearby roads and border facilities at a time when the Canadian dollar was rebounding from the global financial meltdown in 2008. The stronger Canadian dollar and improved traffic flow through the border are factors in the traffic increase.

"I don't hear as much complaints about the border as I used to," said Pettinger, who also noted that he thinks Whatcom County has nearly reached the peak in border traffic unless other changes take place.

Reach Business Editor Dave Gallagher at 360-715-2269 or dave.gallagher@bellinghamherald.com. Read his business blog at blogs.bellinghamherald.com/business or follow him on Twitter at @bhamheraldbiz.