For some reason American Airlines sent me an email about carry on limits. I don't think anything changed so it's confusing why they sent the email. But just in case anyone wanted a refresher, they put a link to the requirements which basically states:
I took a look at the Aeronaut details and it appears to total 45".How Much Can I Carry On?
Dimensional Inches Diagram You can carry on one bag plus one personal item per passenger as long as:
They weigh no more than 40 lbs/18 kgs
The bag is no more than 45 inches and the personal item is no more than 36 inches when you add the length + width + height so that it fits in an overhead bin or under the seat