Watch 48 Years of Classic Super Bowl Ads

It’s no secret that in 2015 it costs a small fortune to secure a 30-second Super Bowl ad spot. According to NBC, the average price of one of those coveted slots was a record $4.5 million for Super Bowl XLIX, or $4.4 million each for multiple spots. All commercials during the game broadcast are now sold out.

It wasn’t always that way. In 1967, at the first Super Bowl, a 30-second ad cost $37,500, which is about $266,000 in current dollars. Not cheap, sure, but a far cry from today’s prices. How long did it take for the big game’s advertisers to make the jump from paying several tens of thousands to several millions? Watch Slate’s history of the Super Bowl ad to find out.