COMMENTARY

NBC's "ER" wraps up a 15-season run tonight with a two-hour episode that's unlikely to draw the kind of crowd the show once did.

But whether you plan to watch or not, here are 15 reasons you might remember "ER":

1. Millions of us have sat in that waiting room.

The series' ratings peaked in Season 2 — one of three seasons it was No. 1 in the Nielsens and one of 10 it was in the Top 10 — with an average weekly audience of 32 million viewers.

You could light "American Idol's" Ryan Seacrest up like a firecracker and make him do the cha cha on "Dancing with the Stars" and you might not get that many people to watch for even one night, much less an entire season.

2. George Clooney.

Before "Grey's Anatomy's" McDreamy, there was "ER's" Doug Ross, the womanizing pediatrician who questioned authority at every turn.

Before Ross, there was just a guy named Clooney, who'd been working in television for a decade with barely a ripple.

The actor, said "ER" executive producer John Wells, "never asked, as the show took off, to make a dime more than he was paid at the beginning, completely fulfilled his contractual obligations to us over five years, stayed committed, did publicity, worked hard, and was just a completely standup guy."

And now he has an Oscar.

3. Matter-of-fact diversity.

"ER" began with just one major character of color — Eriq La Salle's Dr. Peter Benton — but grew to a truer reflection of staffing in a big-city hospital.

4. It took viewers to Africa. And, OK, Hawaii.

Though the Congo-based storyline in Seasons 9 and 10 was filmed in Hawaii — the same place Dr. Mark Greene (Anthony Edwards) went to die — South Africa's Kalahari stood in for the Sudan in Season 12's "Darfur."

5. Its willingness to let characters go.

"We sort of felt like, 'Wow, as soon as people start to leave, that will be that,"' Wells told reporters last summer on the show's Warner Bros. set.

"Then, we were able, because of the success of the show, to replace the actors who were leaving with really extraordinary actors," he added.

6. Its willingness to let those who stayed grow and change.

No one's done more in the growing and changing department than Noah Wyle's Dr. John Carter, who began as a medical student and returned this season for a kidney transplant after years of working in Africa.

Thursday's finale will involve the achievement of one of Carter's long-held dreams, but he's just one of the "ER" veterans who matured before our eyes, from Parminder Nagra's Dr. Neela Rasgotra to Mekhi Phifer's Dr. Gregory Pratt.

7. For better or worse, it helped change the business.

Deals like the record-breaking one Warner Bros. made to keep "ER" on NBC for $13 million per episode almost certainly had a chilling effect on relations between networks and outside studios, encouraging broadcasters to seek control of more shows.

8. It shone a light on the nation's health-care crisis.

Not that it fixed anything.

"We're actually in worse shape than we were ... when we first started doing the show," Wells complained.

9. May have been the first scripted show to mention the current president.

A few seasons ago, "We had a woman in here screaming about how she wanted Barack Obama to come and solve her problem for her," recalls executive producer David Zabel.

10. It gave us news we hope we'll never have to use.

Joe Sachs, an emergency-room doctor and executive producer, tells this story:

"When Mark Greene's brain tumor came back, I had to come up with a way to dramatize it ... He bit his tongue because he couldn't control (it) ... So about a year after that episode was written, I got a letter from a young woman in Texas who was having terrible headaches, and none of the doctors were taking her seriously. They said, 'It's stress. You've got two little kids,' and her tongue was protruding to the side. So when she saw that, she went to the ER and demanded a CAT scan. She had a huge tumor that was growing behind her nose that was a millimeter away from her spinal cord. Two weeks later she would have been dead. She had surgery. She's still alive."

11. The guest stars.

Twenty actors have been nominated for Emmys for appearing on "ER," and though only Sally Field and Ray Liotta have won, many of the performances have been extraordinary, from Bob Newhart's as a man losing his sight to Don Cheadle's as a medical student with Parkinson's.

12. It made a balding guy a chick magnet.

Dr. Greene may not have gotten the action of Dr. Ross, but he never wanted for female attention. Lack of hair also helped freeze him in time, making this season's flashback with Dr. Cate Banfield (Angela Bassett) that much more believable.

13. It fought boredom by taking chances.

In 1997, that meant a live show. In other years, responding to the dictates of sweeps, it meant maybe a few too many explosions.

14. It presented sick and disabled people as more than patients.

La Salle's Benton had a son, Reese, who was hearing-impaired, Jeanie Boulet (Gloria Reuben) was HIV-positive and Laura Innes' Dr. Kerry Weaver walked with a limp that was barely discussed.

15. It stayed put.

Doesn't sound like much, but how many long-running shows get to stay in the same time slot for their entire run?

WHEN TO WATCH

'ER' finale

9 tonight

NBC