Over the last 60 years, recessions have often accelerated transitions in media consumption that were already underway. Since 1950, America has experienced eight sizable recessions. Not every one hurried a media transition, but precedents illustrate what happens when a secular decline coincides with a sharp economic downturn.

Historically, broadcast TV grew in the post-1954 years--it was seen as a new and innovative ad and programming medium. Today, it is experiencing a strong downturn. By contrast, cable--which came into its own in the 1990s--can save its bacon by building an interactive platform that effectively merges TV and Internet offerings.

Delivering interactive advertising on a national basis could lead to renewed growth for cable ad revenues and ad share after the economic downturn. But it's an open question whether the cable companies will be able to deliver in time to catch the upswing once it starts, according to Tim McElgunn, a chief analyst with Pike & Fischer.

"Given the immense complexity of first creating such a platform and then using it to disrupt the existing advertising food chain, it will take years and many millions of dollars in capital spending before its impact will be sufficient to allow cable to capture more than a small percentage of total ad spending," McElgunn warns.

Here's how it shakes out historically:

The first alignment of media innovation and economic woes came in the early 1950s, when television was on the rise, along with inflation caused by the Korean War. The recession from 1952-1953 began when the Fed raised interest rates to combat inflation, rattling consumer confidence and leading to decreased demand.

In the short term, advertisers played it safe, withdrawing dollars from the relatively untested new medium of television. But once the economy recovered, broadcast TV revenues surged from about 5% of total ad spending in 1953 to 15% in 1954. Broadcast TV's growth came at the expense of newspapers, magazines, radio and outdoor advertising, which lacked video's crucial combination of sight, sound and motion.

Television weathered subsequent recessions well compared to the other traditional media. For example, during the deep recession sparked by inflation and the oil embargo in the first half of the 1970s, broadcast revenues shrank from 18.4% of total ad spending in 1970 to 16% in 1974--then quickly rebounded, continuing their upward trajectory into the 1980s.

Broadcast TV was also relatively unaffected by the "double dip" recession of 1979-1982: While its share of total ad spending slipped from 21% to 20.1%, broadcast TV revenues actually increased from $10.1 billion in 1979 to $13.4 billion in 1982. It soon recovered its percentage share of total ad spending as well, rising to 21.7% in 1984.

This would prove to be a high watermark for broadcast TV, however.

The recession of 1990-1991 jolted broadcast TV--initiating a long, steady decline in its share of total ad revenue, which sank from 20.6% in 1990 to 18.2% in 1995. Just as broadcast TV had grabbed ad share from newspapers, radio and outdoor advertising for decades, the changes surrounding the early 1990s recession saw broadcast lose ad dollars to two newcomers, cable TV and the Internet.

Significantly, where the trend lines for broadcast TV and newspaper ad share were crossed from 1950-1990 from 1990 onward, they have run in parallel declines.

Cable TV had been growing as an ad medium since the 1980s, but it really took off in the aftermath of the recession of 1990-1991, with ad revenues growing from $1.9 billion in 1990 to $15.4 billion in 2000. Like TV in the second half of the 20th century, it continued to grow through the recession of 2000-2001, jumping to $16.3 billion in 2002 for an ad share of about 6.9%--growing to 9% by 2005.

As we approach the next shakeout, however, cable TV's prospects for future revenue expansion seem to have dimmed considerably. Growth in Internet advertising--made possible largely by cable connections--was delayed only slightly by the recession of 2000-2001, and returned with a vengeance in subsequent years. Like TV in 1952-1953, the Internet was briefly abandoned by cautious advertisers in 2000-2002, only to explode when economic conditions improved by 2003.

The rate of growth in cable TV ad revenues, by contrast, appears to be slowing.

In the past, one useful indicator of a medium's overall vitality has been its growth rate coming out of a recession. In 1976, broadcast TV--still king of the hill--came out of the prolonged downturn with a 27.4% year-over-year growth rate in 1976. But as competition from cable intensified, broadcast's comeback from the early '80s recession was a more modest 17.8% annual growth rate in 1984, and during its comeback from the early '90s recession, growth was just 10.8% in 1994. Its 2004 comeback growth rate was 8.6%.

Although there is less data available because the time span is shorter, cable TV revenues seem to be showing a similar trend. From an 82% growth rate in 1994-1995--when cable ad revenues added about $3.6 billion--their 2003 comeback growth rate was more modest 15.3%, adding $2.5 billion.

If history is an accurate predictor, this suggests that cable TV has also given up its position as ad innovator and is headed either for a prolonged period of flat ad share or a possible decline in the next few years, once the prop of political ad spending is removed, and despite the growing popularity of original cable programming.

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