Final answer:
Most naturally occurring lakes in North America are found higher in mountains or at latitudes above about 45° N due to elevation and temperature gradients.
Step-by-step explanation:
The reason most naturally occurring lakes in North America are found either higher in the mountains or at latitudes above about 45° N can be explained by elevation and temperature gradients. In higher elevation areas, the cooler temperatures and increased precipitation contribute to the formation of lakes. At latitudes above 45° N, colder climates and a lack of evaporation due to lower temperatures create conditions suitable for lake formation.