Ironically, Madagascar ($193 million) pretty much equaled the box office of Ice Age 2: The Meltdown ($195 million), while Madagascar 2: Escape to Africa ($180 million) grossed just $4 million more than the original Ice Age ($176 million). Internationally, the two franchises are within about $100 million of each other. And, let's not forget, Ice Age is the only animated franchise outside of the Shrek films to actually make it to a third chapter (third chapters for Toy Story and Madagascar are currently in development or production). Point being, people genuinely like this series, so it shouldn't be a surprise if it ends up defeating Transformers: Revenge of the Fallen for the crown over the long Fourth of July weekend.
It's an odd thing, really, how few theatrical animated franchises there are. You could count the animated features that spawned animated sequels on less than two hands. You have An American Tail, Peter Pan, The Jungle Book, Shrek, Toy Story, Ice Age, Madagascar, and that's about it for now. Granted, Kung Fu Panda 2 and Cars 2 will arrive in sumber 2011, but it's interesting that in this franchise and sequel-drenched age, we have so few sequels to cartoons, arguably among the most expensive properties around. It's nice to know that there is one branch of Hollywood where originality theoretically rules.