At this point, foreign oil accounts for roughly half of America's trade imbalance, and that's only going to get worse.
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.