Actually, you are only counted as unemployed if you are looking for work through the unemployment office. The only reason to do that is to collect your unemployment insurance. Once that runs out, even if you're looking, there's no point to go through the government office, so you're not counted.

Sometimes in hard times Congress passes an extension to unemployment benefits- this has the unintended consequence of raising the unemployment numbers, because people who have been out for more than 6 months show up again at the unemployment office.