Rick Bowmer
People in Oregon wait in line for a job fair. A recent Gallup poll shows that confidence in the U.S. economy dropped last week.

Confidence in the U.S. economy dropped from a four-year high of -18 to -21 in the week ending March 18. Confidence in the economy failed to top its previous highs of -18. Economic confidence is almost the same as it was during the same week last month, when it was -23, according to Gallup.

Americans' confidence in the economy reached its highest point since Gallup Daily Tracking started in 2008. The exact reason for the slight drop in economic confidence is hard to determine, according to Gallup. One possible cause could be the consistent rise in gas prices. Gas prices are quickly approaching $4 a gallon, and they're expected to pass $5 a gallon in parts of the U.S. in the coming months.

Even with the continuing surge of gas prices, confidence in the U.S. economy is still significantly better than it was during this same week last year, when it was -31, according to Gallup. The Gallup Economic Confidence Index has two components: Americans' rating of the state of the current economy and their views of whether the economy is getting worse or better. Slight drops in both areas were responsible for the recent drop.