Why does U.S. import oil from the Middle East if Canada has resources of oil?

The United States imports oil from the Middle East because they want to save their resources, in essence. They make enough to support the vast needs of the country, but don't use it up. There have been times in history, as the oil crisis, when the US was vulnerable to the whims and prices of the Middle East.

That took place in the 70s and wreaked havoc across the nation. The US vowed to prevent a repeat and doing so required them to import rather than use up all their supply. Oddly enough, the US exports oil as well.