When you use billboards, you must remember that the sale has to be made in an instant.

They can't even use billboards, or ads on public transportation, or sell clothing with their logos, even to adults.

A host of companies, including both Home Depot and Microsoft, are even starting to use outdoor billboards to seek job candidates.

Even given this limitation, some studies have found higher crash rates in the vicinity of advertising using variable message signs or electronic billboards.

And using billboards as an activist canvas isn't a new revolutionary tactic either.

Over the years the church has used television and radio commercials, billboards, newspaper advertisements and direct mail.

In 2007 they started using billboards in places around Utah to advertise their group.

Some billboard bicycles use large billboards; however the size of the billboard is limited by wind constraints.

"He has to start using billboards rather than the back of his head to make his point," Leonard said.

That meant using not only promotional television spots but also billboards, ads on the sides of buses and posters at bus stops.