The "Buy American" clause in the final version applies only to steel and iron. It states that all infrastructure projects funded by the recovery bill use only U.S. manufactured steel and iron.
That's it. All other products can be imported.
According to the US State Department profile on Canada:
http://www.state.gov/r/pa/ei/bgn/2089.htm<snip>
Trade: U.S. merchandise exports to Canada (2007)--$248.9 billion: motor vehicles and spare parts, industrial and electrical machinery, plastics, computers, chemicals, petroleum products and natural gas, and agricultural products. In 2007, 65% of Canada's imports came from the United States. U.S. merchandise imports from Canada (2007)--$313.1 billion: motor vehicles and spare parts, crude petroleum and natural gas, forest products, agricultural products, metals, industrial machinery, and aircraft. In 2007, 76% of Canada's exports went to the U.S.
U.S.-CANADA RELATIONS
The relationship between the United States and Canada is the closest and most extensive in the world. It is reflected in the staggering volume of bilateral trade--the equivalent of $1.5 billion a day in goods--as well as in people-to-people contact.
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So, Canada exports more than $310 billion annually to the U.S.
However, not all of that is steel/iron that would be affected by this "Buy American" clause. In fact, only about 2.5% of the $310 billion would be affected.
http://internationaltradecommodities.suite101.com/article.cfm/us_steel_imports_exports<snip>
Iron and Steel Exports to US by G7 Country
Canada sends the most ferrous metal exports into America, half of the G7’s $14.4 billion total exports to the U.S.
Canada ... US$7.6 billion in iron and steel materials and products
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So, of the ~ $310 billion annually that Canada exports to the U.S., just $7.6 billion of it is iron/steel.
That's less than 2.5% of the total of Canada's exports.