So do you think that Canada's much lower corporate tax rate might explain this?

Canada's corporate tax rate is 21 percent. Stephen Harper's campaign promise was to cut the rate further, down to 16 percent. From the WSJ:

Canada's economy expanded at a 3.9% annualized pace in January through March, the fastest clip in a year and more than double the rate in the U.S., as businesses replenished inventories and boosted investment spending and exports rose while consumer and government spending stalled, Statistics Canada said Monday.

Gross domestic product growth was marginally below the consensus call of 4%, and also undershot the Bank of Canada's 4.2% forecast.

GDP growth accelerated from a downwardly revised 3.1% in the fourth quarter, which was originally reported at 3.3%. The economic performance was the reverse of the U.S. where growth decelerated to 1.8% in the first quarter from 3.1% previously. . . .

The economy expanded 3.2% in 2010, revised up a tad from the previously estimated 3.1%. . . .

Meanwhile for the United States: "Economists Downgrade Prospects for Growth"

After a disappointing first quarter, economists largely predicted the U.S. recovery would ramp back up as short-term disruptions such as higher gas prices, bad weather and supply problems in Japan subsided.

But there's little indication that's happening. Manufacturing is cooling, the housing market is struggling and consumers are keeping a close eye on spending, meaning the U.S. economy might be on a slower path to full health than expected.

"It's very hard to generate a rapid recovery when rapid recoveries are historically driven by housing and the consumer," said Nigel Gault, an economist at IHS Global Insight. He expects an annualized, inflation-adjusted growth rate of less than 3% in coming quarters—better than the first-quarter's 1.8% rate, but too slow to make a meaningful dent in unemployment.

A growing number of forecasters are downgrading their second-quarter growth predictions. JPMorgan Chase & Co. economists revised down their estimate to a 2.5% rate from 3%, while Bank of America Merrill Lynch economists cut theirs to 2% from 2.8%. Deutsche Bank cut its forecast to 3.2% from 3.7%.

Companies are similarly cautious. Applied Materials Inc., the largest maker of machines used in producing computer chips, said it expected growth in its semiconductor and solar markets to slow following one of its best quarters ever. Hewlett-Packard Co. cut its fiscal-year outlook amid weak computer sales and negative effects from the disaster in Japan. Clorox Co. offered a more guarded outlook for its household goods business as executives noted that higher prices may hurt sales.

The dimming outlook raises a deeper question about the economy's health: Has it emerged from the financial turmoil of 2008 and 2009 with a chronic growth problem?

Some economists think it has. "We keep expecting the economy to perform along norms that are very difficult to achieve when you have this much private debt and public debt," said Carmen Reinhart, an economist at the Peterson Institute for International Economics. . . .