For this application, as was stated, it's probably not vital to know the exact latitude, longitude, since distance in pages in the census should be good enough. Because of the way the census is taken, two families on the same page or on consecutive pages and in the same township are close together. However, I thought I would share something I found the other day that I plan to use in a genealogy app I'm working on. I found open source data so one can make their own geocoder:
http://www.geonames.org http://www.geonames.org/export/ There are other open source Geocoders out there, but they tend to be based on the U.S. Census data, which means they only work for U.S. addresses. I have found one other free data source that has the place names and latitude, longitude for the entire world, but it isn't nearly as clean and complete as this one. Jay On 8/20/07, Thomas Haws <[EMAIL PROTECTED]> wrote: > I'm a civil engineer. > > What we often call GPS is officially "geographic coordinates" or "latitude > and longitude". GPS is more correctly the satellite system that allows > real-time, map-free positioning. GIS (geographic information system) is a > database that has coordinates on everything. > > Two ways to get the geographic coordinates (lat and lon) for an event are: > > 1. Manually determine where the event fits on a modern map or aerial photo > (Google Maps) and pick off the coordinates. > > 2. Lookup the location identifiers (zip code, address, point of interest) > in a geo-coded database, or GIS. > > Latitude and longitude are by definition stable across time with 0 degrees > longitude running through Greenwich, England. > > The difference between the two canonical precise datums, NAD27 and NAD83/WGS > 84 is insignificant for genealogy work. > > BOTTOM LINE: > I don't know if old systems like the censuses and old town names have been > geocoded by date into GISes. But putting latitude and longitude into > genealogical event data would be a wise move. > > Tom > > _______________________________________________ > Ldsoss mailing list > [email protected] > http://lists.ldsoss.org/mailman/listinfo/ldsoss > > _______________________________________________ Ldsoss mailing list [email protected] http://lists.ldsoss.org/mailman/listinfo/ldsoss
