Latinos in the heartland : proceedings of the 12th annual conference : positive steps toward a pluralist society, St. Louis, Missouri, June 12-14, 2013 / Stephen Jeannetta and Corinne Valdivia, editors ; with the assistance of Katarina Sostaric and Lindsey Saunders. (OCLC #889753646)
The record for this title includes the subject headings:
650 0 ǂa Hispanic Americans ǂz Middle West. 651 0 ǂa Middle West ǂx Emigration and immigration.
The MARC field 043 (Geographic Area Code) is used if a subject heading assigned to the item has a geographic term in any form or position.
The code for Middle West (on the MARC Code List for Geographic Areas) is:
043 __ ǂa n-usc--
You can generate these fields quickly in OCLC (from the 6XX) using the macro OCLC!Generate043.