To recline or not to recline? Airplane "legroom wars" are prompting growing rage in the United States, with two recent seat battles sparking a heated debate about the knee-bumping practice.

Amid the furor, one thing everyone seems to agree on is that space on passenger planes is getting scarcer and scarcer.

The question of reclining etiquette "has been a topic of discussion for many years," said Sarah Schlichter, editor in chief of IndependentTraveler.com.