According to the September Gallup Poll, it was starting to look like the approval rating for Congress might be creeping upward finally. That poll showed a 19% approval rating (including 18% from Republicans, 19% from Independents, and 20% from Democrats). While very low, those numbers look pretty good when compared to other recent numbers for Congress.
But then the dysfunctional Congress shut down the federal government, and a new Gallup Poll (taken between October 3rd and 6th of 1,028 nationwide adults, with a 4 point margin of error) showed an 8 point drop in approval (to 11% -- only one point above the poll's all-time low for Congress). And all political persuasions showed a drop in congressional approval (3 points for Republicans, 6 points for Independents, and 15 points for Democrats).
This has also resulted in a yearly average for congressional approval of 15% -- the lowest yearly average the Gallup Poll has shown for Congress since they have been polling on them.