The list of top publications in Geography & Cartography on this page is generated by Google Scholar Metrics. Google Scholar tracks how often articles from a particular publication are cited in other articles. Generally, the number of times an article is cited indicates is the article's importance in a field of study; a single journal or publication that has many articles that are cited frequently may be considered to be a top journal in the field because its research is influential.
You can look up specific publication rankings, as well as see periodical rankings in other fields, at Google Scholar.
Another frequently used metric to indicate a journal's prominence in the field is Impact Factor, which is calculated in a similar manner to the Google Scholar metric of a journal:
The Impact Factor is calculated by dividing the number of citations in the JCR year by the total number of articles published in the two previous years. An Impact Factor of 1.0 means that, on average, the articles published one or two year ago have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published one or two year ago have been cited two and a half times. The citing works may be articles published in the same journal. However, most citing works are from different journals, proceedings, or books indexed by Web of Science.
The database Web of Science Journal Citation Reports (JCR) is a widely recognized index of impact factors (however, this database is unfortunately not available full-text at CSUN). Many journals, however, do list their JCR Impact Factor on their website.
Scimago is another journal ranking system that uses the same basic concept with a slightly different formula, called the H index. Their freely available rankings also list Progress in Human Geography as the top journal, but diverge from there.