A visitor visa is available to enter the United States as a tourist. This application is made with the US consulate or embassy in Mexico. You can find a list of locations at http://www.usembassy.gov/. You can also read more information about how to get an appointment at the Mexican embassy, and the details about applying for a visitor visa, at the embassy website at http://mexico.usembassy.gov/eng/evisas.html.
Your mother in law will be required to prove that she does not intend to stay permanently in the United States, which is known as "non immigrant intent." She can show this by demonstrating that she has a job, family, home, social and other ties to Mexico.
If you would like legal assistance in helping your mother apply for a visitor visa, or if you are considering having her apply for permanent residency in the United States, please contact us at 206-624-8410.
Global Law Partners LLP
216 First Avenue South, Suite 470
Seattle, WA 98104
(206) 624-8410 English
(206) 624-8402 espanol
(866) 897-8543 fax