PyRo,
The old Winnipeg Jets were really the first ones to start the "wear white" thing...looked sick in a hockey arena...lots of other pro sports teams latched on...
Here is what Wikipedia says...
"The Winnipeg White Out is a hockey tradition that dates back to 1985 when hockey fans in Winnipeg were asked to wear white clothing to home playoff games in Winnipeg, creating a very intimidating effect and atmosphere. It was created as a response to the "sea of red" created by fans of the Calgary Flames, whom the home town Winnipeg Jets were facing in the first round of the playoffs. The Jets would eliminate the Flames in four games, and fans wore white for every playoff game since. Fans coined it the "White Out".
The tradition has since been carried on in Phoenix, where the Jets relocated in 1996 to become the Phoenix Coyotes.
Several other teams have since tried to replicate the success of this tradition. During the 2004 Stanley Cup Playoffs, the San Jose Sharks attempted to create an "ocean of teal" during their semi-final series against the Flames with dismal results. The Philadelphia Flyers gave away orange t-shirts to create an "orange crush" against their semi-final opponent, the Tampa Bay Lightning, who countered with a white out of their own.
Among other teams, Mighty Ducks of Anaheim fans have also attempted the White Out, along with fans of the Buffalo Sabres in the 2006 Stanley Cup Playoffs.
The tradition is also prevalent in other sports, as the student section at Penn State's Beaver Stadium held a white out during the nationally televised football game between Penn State and Ohio State in October 2005. Also, the Miami Heat of the NBA have started a "White Hot Heat" promotion, similar to the White Out."
Cappo