Don't do it... not only is it banned for air travel both domestically and internationally, but if they find it they may hold your entire bag back... have heard of this happening on three occasions. And even if you get it onboard in the US, remember you still have to clear customs in Mexico and when they find something banned it is much worse to deal with. Buy it locally!!!
Also, Mexico is one of the ABSOLUTE WORST countries to bring cigars into... First off, there is an ongoing dispute as to how many cigars you can bring with you Duty Free into the country... some of their own government operate sites claim 50, but others claim 25. As a result, I have been made to comply with 25 count limit about 75% of the time - it is totally willy nilly - it will depend on the customs agent at the moment.
Any cigar over the 25ct (unless you get lucky with the 50ct) will be taxed at 100% the MSRP - they actually go on Google and find the MSRP... so a $350 box of Liga Privadas will cost another $350 in order to bring them in. And to make matters worse, at most points of entry Cabo, Cancun, Mexico City, etc - they will force you to pay in cash in Pesos only.
And if you try to not claim them and they find them, be prepared to be delayed 2 or more hours as they love to detain you and will even go as far as actually arresting you for smuggling. I personally had this experience and had to involve the local consulate and attorney to squelch the situation all over 75 cigars. Thankfully I knew some VIPs who could get this to happen, because who the hell knows what would have happened.
IMO, it is total clusterfuck trying to bring cigars into Mexico.
So my advice is bring 25 or less and CLAIM them.
BR,
STS