As Plutarch observed 2 millennia ago, mapmakers aren't nearly as accurate as they claim to be.
All maps are subjective in that they involve a process of selection and omission.
Bassett and co-author Yvette Scheven, a UI professor emerita of library administration, found and identified more than 2,400 maps, the earliest being a 1508 Portuguese map showing a compressed continent that looks more like Massachusetts than Africa. A Royal Geographical Society map, for European audiences, shows colonies and spheres of influence in 1890. Thus, Dutch maps dominate the collection for the 17th century, while British and French maps stand out for the 18th and early 19th centuries.