For pretty much an entire generation, televisions have been as ubiquitous as living room sofas — but that could be changing.

For the first time in 40 years, the number of households with TV sets has actually dropped, despite the fact that the number of US households in general has continued to grow.

This year’s “Television Audience” report from Nielsen Media Research revealed that three percent of households currently don’t have TVs, the highest level since 1975. The group also predicts that in 2012, the number of households that do have TVs will probably drop one percent.

Why is this happening? Nielsen says that 2009′s transition from analog to digital broadcasting made some people forego their TVs altogether instead of buying a converter box or subscribing to cable. In addition, the downturn in the economy has left rural or lower-income households unable to afford a TV, while others have turned to websites, mobile devices, and other video outlets to watch their favorite shows.

But cable companies, take heart. Experts say that more than half of households with TVs own at least three of the so-called “electronic babysitters” — so die-hard boobtube worshipers haven’t exactly become extinct.

[New York Post]