Writing Region Content is different and separate from the "Category" articles. When writing region content, you are, in essence, geo-targeting a particular region (State, City, Community).
So if you want your category article to target people in San Francisco, CA, you would write some information about the San Francisco area (example: "Authors from San Francisco and their contribution to the writing community," or "Local laws in San Francisco that make post-adoption support challenging").
Keep in mind that.. in essence, the Category Articles are written as "geo-targeted landing pages." Although the bulk of the content will be duplicated across many states and cities all over the country, this Region Content is primarily what really "Localizes" the "geo-targeted" landing pages.
So it's critical to be specific with the local area, when writing your Region content. This includes linking to local entities (meaning businesses, organizations, or clubs). Ultimately, you want both local readers and Google to think your company may be located there. This will act as a good rule of thumb when researching your region content.
In terms of word count, it's recommended that you have approximately 30% of the State category page word-count in the State region content, and approximately 15%-20% of the City category page word-count in your City region content.
As a shortcut, you can split it up by writing half of your content about the local area, and fill the remaining half with a call-to-action and/or quotes. This way, it's easier to meet the demand of all the region content that will populate your website category pages. Don't forget to include a link or two pointing to a relevant local website, this will greatly enhance the SEO for the page.
Resources to Help With Writing:
See examples of what Region content should look like..