Manually made dot maps vs. computer-generated maps
Both types of maps are made from the same records except those for species with abundant Ohio records from the field notes of E. S. Thomas and R. D. Alexander. For these species, many of the Ohio records on the dot maps do not show on the computer-generated maps, because only a representative sample of these records were entered into the Access database.
Each county record gets the same sized dot, making records for even the smallest counties plainly visible.
For counties that are large or extended, the dot can be placed at the appropriate place within the county and more than one dot can be used. For example, in Monroe County, Florida, occurrence is separately indicated for Lower Florida Keys, Upper Florida Keys, and continental Monroe County.
Dots must be manually placed, which is time consuming and subject to error.
Where records are dense and the dots are bigger than the counties, dots must be overlapped or omitted.
All U. S. records in the Access database can be mapped quickly and with total accuracy.
The program that makes the computer-generated maps can make no use of Canadian records.
Records for unusually small counties may not be visible at the scale that is used for maps in SINA (for example, some of the counties on the upper Atlantic coast are that small).
Many of the counties in the West are too large to display distribution at as fine a scale as revealed by county-level mapping in the East.