Quite a bit of stability in the map of North America since the 19th century, a testament to how peaceful the area has been, other than internal strife in Mexico in the first third of the 20th century, and internal strife in Central America in the seventies and the eighties.
It is amazing how few changes were due to conflict. The majority of changes were simply due to the adoption of new flags, land purchases, or voluntary mergers (such as Newfoundland into Canada).
The one complaint I have is the inconsistency of de facto control versus de jure. Greenland gets the U.S. flag during WW2, as does Cuba in 1906-08 and Haiti in 1915-34. None of these occupations were a change of legal sovereignty. Moreover, similar occupations of Nicaragua by the U.S. (1912-33), Guatemala by the U.S. (1920), eastern Greenland by Nazi Germany (intermittently in 1942-44), and the United States by Great Britain (Northwest Territory 1783-1815) are not depicted.