The search is based on geographical codes entered by the editors for each citation. These codes are designed to represent regions (such as Africa, Asia, or Latin America), countries (from Afghanistan to Zimbabwe), or, in the case of the United States, individual states (from Alabama to Wyoming).
Geographical terms change over time. When a country changes its name but remains as one political unit we maintain the code but use the current designation, so entries for Burma will be found under "Myanmar" irrespective of date.
When countries subdivide or combine to form new political units, we create new categories, so entries for Germany will be found under "German Democratic Republic" or "Germany, Federal Republic of" before 1991, but under "Germany" for citations dating from 1991 or later.
A complete list of geographical terms in current use is available in alphabetical order, and is classified by major regional groupings.
Example 1: You are studying the fertility transition in Latin America. Searching for "fertility transition" as a subject and "Latin America" as a region yields 26 hits.
Example 2: You are interested in fertility trends in the USA. You enter "fertility" in the subject field and "USA" in the region field and find no entries under "USA". A quick look at the list of geographical terms leads you to try "United States". You find 1,671 citations.