There is more than one reason for that. First, I have a greater knowledge of (and greater interest in) regions where my ancestors and I have lived. Finally, the web site is always a work in progress; and, it is possible that certain pages have not yet been added, simply because I haven't gotten around to writing them yet.
The primary reason is that local histories (counties and towns) are emphasized more at this site. The reason for this is that the histories at the national or state level have probably already been covered by other web sites. Meanwhile, the histories at a more local level are often the ones most neglected; and, this web site will attempt to fill that niche.
The national and state histories will be updated whenever time and availability of information permit. As was mentioned, national and state histories are not the highest priority of this web site.
Those would be Union County, South Dakota and the town of Beresford, South Dakota. Sioux County, Iowa and the town of Hawarden, Iowa are also of interest.
The web site should always be considered a work in progress; and by its nature, the content of this web site will probably never be completely finished. Also, my first priority is my genealogical research; and, this history web site is merely a spinoff of my genealogical research. Finally, I do have a day job; so, I have to spend a some of my time working to pay my bills, even if it takes away from my research time.
This web site covers quite a variety of towns, anything from a small "country point" (containing nothing more than a general store and a post office) to a large city containing a population of tens (or hundreds) of thousands. Some of the villages are not necessarily incorporated cities. Some of the smaller villages may no longer exist. But, recording and presenting the histories of various geo-political regions is the purpose of this web site; and, no towns are excluded on the basis that they may no longer exist. In fact, the absence of towns from modern maps (or the shrinking of towns) makes it even more important to record those towns' histories before they are lost forever.
Not necessarily. When (for a example) a state's history is presented by this web site, all of the counties are listed in the table for purposes of completeness. If histories for certain counties are written, their names will be linked to the relevant web pages from the state's page.
This site should be regarded as a work in progress; so, some information has not yet been added because it has not yet been found. However, if the starting or ending date for an entity (such as a business) is listed with a "c." (which means "circa"), this merely means that the research shows that the entity is known to have existed during that year. If the starting date is listed with the "circa" symbol, it merely means the entity existed as early as that year but may have existed earlier. A "circa" symbol in the ending date means that the entity existed as recently as that year but may have continued to exist more recently. The "circa" symbol is only used when precise starting and/or ending dates for an entity have not been found.
Unfortunately, it is possible that some of the precise starting and ending dates may never be found. For example, it is far more common for businesses to publish announcements of their first openings than it is for some (especially smaller or shorter-lived businesses) to announce their final closings. In those cases, any "circa" dates provide important information on when the entities were known to have existed. If approximate dates of starting or ending are known, those dates are listed with a question mark.