The U.S. Transportation Security Administration has now detailed its stance on "Transporting Knitting Needles and Needlepoint" more sharply than ever.

In a nutshell, knitting needles are indeed permitted in both checked and carry-on baggage.

"However," according to the in-depth bulletin on the TSA Web site, the needles could be perceived as a possible weapon" by security officers, any one of whom has "the authority to determine if an item can be used as a weapon and may not allow said item to pass through security."

To reduce the risk of confiscation, the TSA recommends that you carry needles made of bamboo or plastic, not metal; that circulars be less than 31 inches in total length; that you have a self addressed stamped envelope with you so you can mail the needles home if they are deemed unacceptable; and that you pack only blunt-edged scissors.

Circular thread cutters or any cutter with a blade contained inside must go in your check baggage only.

To read the official policy:
https://www.tsa.gov/travel/security-screening/whatcanibring/items/knitting-needles