Sorry, guys (and yeah, Congress is mostly made up of guys):
Yeah, even HMOs are more popular than Congress. (I should probably note here that I think that's proper: HMOs work pretty well, and even in the 1990s, when everybody really hated them, they were holding down costs with no evident hit to health outcomes or even to the quality of care. But I digress). Of course, there are institutions Gallup hasn't seen fit to poll. But Public Policy Polling looked into a bunch of those, too, and found Congress is less popular than lice, colonoscopies or Nickelback:
To make a slightly more serious point here, there's a structural reason Congress is so much less popular than any other major institution in American life: It's divided against itself. People often like their own representatives, and they even like the members of Congress from their party. But if you're a Republican who voted for Republicans in Congress you're angry because the Democrats control the Senate. If you're a Democrat who voted for Democrats for Congress you're angry because of the House Republicans. Periods of divided government give everyone a reason to be angry. HMOs don't have that problem.
This house-divided problem wasn't such an issue in the 1950s and 1960s and 1970s because the two parties really weren't that divided. But as party polarization begins to take off in the 1980s and then accelerate in the decades thereafter, the public's confidence in Congress plummets.
The tough question here is whether our system of government needs relatively non-polarized parties to work effectively. Sociologists like Juan Linz note that there are very few political systems like ours, because having competing parties installed in competing parts of government that are all able to wield power and claim democratic legitimacy at the same time has historically been a recipe for instability and, eventually, disaster. America has evaded that fate thus far, but now that our parties look more like parties in other parts of the world, the question is whether we can evade it forever. A House divided against itself will eventually fail to raise the debt ceiling, or do something else really dumb.