6 months. Yes, mexico does count outside of US. they can determine based on the immigration stamp

thank you @Sandra Deriphonse and @Angel K . can I stay more than 6 months separately? meaning come back to the states every couple months for example?

you can as long as you have good reasons. they might ask you questions though if you are doing it like twice a year or so.

Usually not more than 6months. If you plan to stay longer, you should apply and get a re-entry waiver and you still have to prove that you’re still domiciled in the US upon arrival. Even if you Drive to Mexico, there usually a record of that trip when you re enter even if your passport is not stamped(mine usually isn’t when I drive to Canada, not sure about Mexico. Rememebr you have a legal presence obligation to meet to legally obtain naturalization if/when you do decide to file. If you make too many oversea trips on a GC, it’s just a matter of time before someone notices. Beware!!!

@Stanley O thank you Stanley. but I can separate my visits like mentioned above correct? just not 6 months straight?

You can do that but again it’s just a matter of time before CBP notices. You sign up for a trusted travelers program (Global Entry for foreign travelers) that way you don’t even have to talk to cbp on arrival but it’s not guaranteed that you won’t talk to an officer.