I am a us citizen who is living and working in Mexico. I am engaged to a Mexican and would like to marry in the Usa and then return back to Mexico to live. How would I do this? File a K1 visa? Do I have to make a certain amount of money?

Why don't you get married in Mexico... it really makes no difference where you get married... the mere fact of marrying an American doesn't grant you citizenship... or even a right to VISA or green card... they have to make the applications.. pay the fees.. and hope they get accepted like anyone else... and its likely to take years.

Been there, done that. Its not easy, cheap or any fun. In fact it might be the most expensive , frustrating thing you will ever do.

You can get married in Mexico and when it's time to return to US, then you file I-130 for your spouse.

OP says he/she wants to marry in the US, perhaps so that OP's friends and relatives can more easily attend the marriage.

OP is a US citizen and wants a visa for the fiancé.

If OP wants to return to US permanently, he/she can petition K-1 visa for the fiancé, BUT if the OP will continue living in Mexico, he/she cannot petition any immigrant visa for spouse, unless he/she has plan to return to US permanently.

I-130 can be filed 6 months in advance before date of relocation.

If the plan is for the fiancé to enter the US for a short period and return, it wouldn't be an immigrant visa. Can a Mexican citizen obtain a short-term non-immigrant visa?

To get married, perhaps be in US for a few weeks, they come as a tourist, and just get married and return home. They just can not stay in US