Every week I get a couple of e-mails asking "How come you map my QTH in Missouri (or Ontario, or central instead of eastern Russia). Here's the answer -
When we go to plot a dot on the map for a
station that has been spotted, we query QRZ.com. Most of the
time that returns a location we can use, but occasionally it
doesn't. In that case the website defaults to an arbitrary
location for the center of the country as determined by the
performance reasons (imagine a busy contest weekend) and to
avoid wearing out our welcome at QRZ.com, we cache
station locations for a week or so before doing another lookup.
If a station is active, its location will generally be
corrected by the next query after the cache has expired.