Canadians appear to be doing more shopping in the United States.

The number of same-day trips they made by automobile rose 16 per cent in 2011 from the year before. However, the 28 million same-day car trips Canadians made to the U.S. in 2011 pales in comparison with the nearly 60 million made in 1991.

Other evidence of increased cross-border shopping by Canadians comes from sales tax data in the U.S.

Erie County, which borders Canada and includes Buffalo, N.Y., set a record last year for sales tax receipts, which were up 4.5 per cent from 2010. Cross-border shopping was the main reason mentioned by county officials for that increase.

When cross-border shopping by Canadians goes up, it's often attributed to growing strength of the loonie. That was certainly the case in the late 1980s and early '90s, when the Canadian dollar rose 21 per cent and same-day automobile trips more than doubled.

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Cross-border shopping was up last year but it's still a fraction of what it was around 1991. Canadian border guards are silhouetted as they replace each other at an inspection booth at the Douglas border crossing on the Canada-USA border in Surrey, B.C., on Aug. 20, 2009. (Darryl Dyck/The Canadian Press)

However, when the Canadian dollar made its huge run beginning in 2002 and zoomed past parity in 2007, same-day trips by Canadians showed only a slight increase.

"The close relationship between the exchange rate and same-day auto trips from 1986 to 2001 weakened substantially as border security tightened following the September 11, 2001 terrorist attacks and has not been re-established since," according to a 2007 Statistics Canada study.

The combination of currency movements and increased security did cut in half the amount of cross-border shopping by Americans in Canada, according to the StatsCan study.

Statistics Canada uses same-day automobile trips as its main measure of cross-border shopping, but does note that some of those trips are for other purposes.

Here are more figures on cross-border shopping.

140,728 — Number of cars and other vehicles that crossed the border daily  in 2010

300,000 — Approximate number of people who cross the Canada-U.S. border daily.

28,462,677 — Total same-day automobile trips by Canadian residents to the U.S. in 2011 (20.4 million counted by vehicle; see table above)

49,983,631 — Total trips by Canadians to the U.S. in 2011

57 per cent — Share of Canadian trips to the U.S. that were same-day car trips

3,446,000 — Number of overnight visits by Canadians to New York state, the state that received the most visits by Canadians, as well as the state with the highest number of visitors to Canada in 2010

$4,924,000,000 — Amount Canadians spent in the U.S., third quarter of 2011 (up 8.5 per cent from the third quarter 2010)

$72 — Average spending per person per same-day trip by Canadian visitors to the U.S., 2009