The power of the press often surfaces in subtle ways.

For the past three years, The Mirror has covered happenings on Black Friday — the ultimate shopping day that starts the morning after Thanksgiving.

In 2006, a woman escaped serious harm after people trampled her as they poured into Wal-Mart in Federal Way.

The woman screamed and reached helplessly while single-minded shoppers stepped on, over and around her. Bystanders outside the store’s entryway shouted and pounded the glass as a potential tragedy unfolded over the course of about 10 seconds. We watched in relief as the woman limped into the store once employees pulled her to safety.

In 2007, the scene on Black Friday took a different tone. Shoppers as well as Wal-Mart employees talked about seeing last year’s trampling on the front page of The Mirror.

When the doors opened this time, shoppers filed in peacefully. Same thing at Target and Best Buy, two other Federal Way stores where shoppers line up early.

In 2008, the trampling from two years before started coming up in conversations again. Apparently, people remembered.

With camera in hand, I checked out local hot shopping spots before the doors opened. At Wal-Mart on 314th Street, the line wrapped around the store. Although the crowd seemed calm, that vibe became unstable as soon as the clock struck 5 a.m. People at first flowed steadily into the store, but then the pace quickened. People quit walking and started to gallop like a herd whose collective behavior could take over at any moment, almost like a match that could ignite a frenzy nobody wanted to see. Aside from a few irked shoppers who chastised those who cut in line, there was no drama or violence — thankfully.

The effects of that trampling depicted on our front page can still be felt today. If the photo and report prevented more tramplings, then we did our job.

Shortly after the photo ran, two Federal Way Wal-Mart managers visited The Mirror’s office. They were not pleased with the photo and the negative light it likely cast on their store.

However, I knew right then that another Black Friday trampling was less likely to happen again on their watch.

Whoever chose our newspaper’s name surely kept in mind one of the media’s chief goals: To hold up a mirror to society. Sometimes all it takes is a good look in the mirror to see what needs to change.

Mirror editor Andy Hobbs: editor@fedwaymirror.com