Changes in retail tobacco promotions in a cohort of stores before, during, and after a tobacco product display ban.

We used a longitudinal design to investigate the impact of a government policy banning the display of tobacco products at the point of sale. The extent of tobacco promotions in 481 randomly selected stores was documented at 4 points in time (2005-2009). Tobacco promotions were greatly reduced after implementation of the display ban. A ban on the display of tobacco products and other signage and promotions at retail is a critical tobacco-control policy to reduce people's exposure to tobacco marketing.