At this point, foreign oil accounts for roughly half of America's trade imbalance, and that's only going to get worse.
The U.S. trade deficit—the difference between the value of the stuff America exports and the stuff it imports—has been in record-high territory since around 1997, hitting a peak around 2006. And if you're one of those people who thinks the trade deficit is a problem (there's some debate) you might want to reevaluate how much you drive.
The chart above, from Calculated Risk, shows the monthly U.S. trade deficit in total (the blue line) and the trade deficit minus the amount America spends on foreign oil (the red line). As you can see, oil has become a bigger and bigger part of the trade deficit since around 1999. At this point, we could cut our monthly trade deficit in half if we didn't buy any foreign oil. While it's unrealistic to think we could stop buying foreign oil tomorrow, it isn't that hard to do your patriotic duty by driving less, buying less plastic, advocating for energy efficiency measures, or supporting your local wind farm project.
UPDATE: As BDHECKS pointed out in the comments, I had the colors reversed at at first. The post has been corrected.