It's March for Life day and, during a rather busy teaching day here in New York City, I have been trying to pay attention to some of the live-streams of coverage from Washington, D.C.

So far, I have not seen any edgy websites or cable shows manage to get "president," "prostitute" and "pro-lifers" into the same headline or info graphic, but I won't be shocked if that happens.

President Donald Trump's speech to the marchers -- via video hook-up -- pretty much guaranteed this year's event would get more mainstream ink than it has in the past. As always, politics is worth more coverage than piety or poignant personal stories (the kind told, year after year, by the "I regret my abortion" activists).

Nevertheless, the March for Life remains what it has been for decades -- the Olympics for researchers studying media-bias issues (click here for a collection of GetReligion posts on this topic). I think it would be helpful to pause and look at the history of that, as we await some of the headlines and trends from this year.

During my early 1980s graduate work at the University of Illinois in Urbana-Champaign, I looked at quite a few of the articles and photo-analysis studies that already existed contrasting mainstream media coverage of these giant anti-abortion rallies and other Washington events on other topics.

Then, in 1990, everything changed.

That was when the late, great media-beat reporter David Shaw of The Los Angeles Times wrote his ambitious series on media-bias issues tied to abortion. Ever since, any significant discussion of March for Life news coverage has included some kind of reference to this story: " 'Rally for Life' coverage evokes an editor's anger." The overture is long, but essential:

The Washington Post is "institutionally 'pro-choice,' " the Post's ombudsman, Richard Harwood, wrote. ... "Any reader of the paper's editorials and home-grown columnists is aware of that." But "close textual analysis probably would reveal that, all things considered, our news coverage has favored the 'pro-choice' side," too, Harwood conceded.