History behind the Chicago Cubs 'W' flag

CHICAGO (WLS) -- All across Chicago and beyond, the "W" flag is part of the Cubs victory battle cry.

Cubs Win! Photos of players, fans celebrating

In 2010, the Blackhawks were even recognized as the Cubs hoisted a modified red "W" flag for the Stanley Cup champs.

But where did this tradition come from? Well, Cubs fans have one man to thank: Bill Veeck.

"The one thing that P. K. Wrigley would let him do, in terms of advertisement, was to have lights at the top of the flagpole," said Peter Alter, a historian at the Chicago History Museum.

Back in the late 30s, baseball fans who rode the "L" would roll past Wrigley could just look up to the lights to see who won.

"Green meant that the Cubs won," Alter said. "And a red color meant that the Cubs lost."

In the 40s, flags became the informer for baseball fans, and so the "W" flag was born.

We should close with this: there's also a much less popular "L" flag. It's blue, not white, and it flies, well... Seems obvious, no?