Friday is National Wear Red Day, where Americans are encouraged to wear red to support heart health awareness.

Heart disease is the No. 1 killer in America, especially among women.

The day is an initiative of the American Heart Association’s Go Red For Women campaign, which launched in 2004. Since then, businesses, cities and even landmarks have gone red to show support. Some of the tourist attractions that participated in last year’s Wear Red Day included Graceland, the Los Angeles International Airport and Times Square.

Some companies that participated in last year’s Wear Red Day -- and some of which raised the most money for heart health awareness -- include Morgan Stanley, Panasonic, ING, TD Banknorth, Pepperidge Farm, Trump International Tower & Hotel and Visa.