Voldemort had to fly out because Nurmengard had anti-Apparation wards. It wasn't a matter of getting within "range" of the Malfoy Manor, but of getting to the closest area that would allow him to Apparate.Originally Posted by hogwartsbookworm
I would agree with Apollonious that there is no actual maximum range for Apparation. The limiting factor would instead be the risk of splinching, which I image would increase with distance and a lack of skill. So though I believe you could Apparate across the Atlantic if you wanted to, you'd have a ludicrously high chance of injuring or killing yourself. Missing your destination would be the least of your worries.
Tim the Enchanter