HOLLYWOOD — By all accounts, crime rates in this country are down, but you’d never know it by turning on your television set.

For the first time, TV’s most-watched series is a crime drama — CBS forensics phenom “CSI” — and its success has ushered in a primetime crime wave unprecedented in tube history.

Whether it’s a crime-based miniseries, the O.J. Simpson trial or talking heads filling up hours on cable news nets discussing the latest Jon Benet Ramsey or Laci Peterson story, Americans have always loved a good murder mystery.

But this fall, we’ll find out if the nets have overdosed on a good thing.

Reminiscent of the late 1950s, when roughly half of the most-watched programs on television were Westerns, procedural crime shows are everywhere you turn this fall — including, for the first time, in the “family hour.”

Five years ago, there were eight primetime programs with a crime or cop element, and by 2001 there were 11. This season, that number will mushroom to 19 — 20, if you count NBC’s “Crossing Jordan” at midseason.

Cable nets also contribute to the wave, with shows like HBO’s “The Wire,” FX’s “The Shield,” A&E’s “Cold Case Files,” Discovery’s “FBI Files” and Court TV’s “Forensic Files.” Also, Lifetime last week premiered a drama, “1-800-Missing,” that at least sounds like it was inspired by successful CBS rookie “Without a Trace.”

For CBS, whose latenight slogan in the ’80s was “Crimetime After Primetime,” it’s now pretty much “Crimetime in Primetime.”

Net has grown from two crime hours to eight in just two years, and this doesn’t count newsmag “48 Hours Investigates,” whose focus was shifted to crime stories last year.

“Yes, we have a lot of crime, but the public is responding to it,” CBS topper Leslie Moonves said recently, pointing out that the two most popular new shows of the 2002-03 season were his net’s “CSI: Miami” and “Without a Trace.”

You can’t argue with that.

“CSI” likely had its peak season last year when it averaged 26.2 million viewers weekly, but it figures to be at or near the top of the ratings heap for several years.

And, of course, it’s spawned one official spinoff, “CSI: Miami”, and others cut from similar cloth, such as “Without a Trace,” both of which could see second-year growth next season.

This fall, CBS is adding its fourth Jerry Bruckheimer crime hour, “Cold Case,” as well as “Navy NCIS” and “The Handler.” Both “Cold” and “NCIS” will air in the 8 o’clock hour.

From a ratings standpoint, you can certainly understand the Eye’s crime-ridden lineup. Such shows repeat well, usually draw more males than typical dramas and are generally speaking a safer bet than character-driven fare.

NBC also has a pulse on crime, skedding five hours this fall including its three-pronged “Law & Order” machine. But it, at least, has a better mix of other dramas.

ABC, which has been struggling in the drama department with offbeat and relationship-oriented skeins, appears to be playing it broader and safer by adding cop shows “Karen Sisco” and the lighter “10-8”.

The WB is also taking a dip in the Bruckheimer crime pool with midseason’s “Fearless,” which seems out of character for the mostly blue-sky net.

You have to wonder what the cumulative effect of all this crime will be on viewers.

Will we see a backlash similar to the current reality wave in which only the unique survive? Or might viewers, looking for something different, start gravitating to more relationship-driven skeins?

We’ll have a better idea in a couple of months.

Next week, Variety begins its annual night-by-night analysis of the new season.