It turns out that the massive rise has only occurred in the past few years. Kevin Drum captions:
What's fascinating, to me, isn't that the costs of presidential campaigns have skyrocketed so much, but that they haven't. Until very, very recently, that is. From 1964 all the way through 2000, the cost of presidential campaigns was pretty stable, ranging around $300-600 million in inflation-adjusted terms. It was only in 2004 and 2008 that costs suddenly went through the roof. I wouldn't have guessed that. I always figured that campaign costs had been rising inexorably for decades. But apparently not. They've only been rising inexorably for the past eight years.(Image via Mother Jones)