Final answer:
John Cabot was the first person to map Canada's Atlantic shore, making his discovery in 1497 while exploring under the English flag.
Step-by-step explanation:
The first person to map Canada's Atlantic shore was John Cabot, an Italian navigator and explorer who sailed under the English flag. Cabot embarked on his voyage in 1497, shortly after the first ventures of Columbus, and he is attributed with the discovery of the northeast coast of North America. Although Giovanni da Verrazzano was commissioned to find a northwest passage, and Jacques Cartier claimed the mouth to the St. Lawrence Seaway, it was Cabot who is recognized for mapping the Atlantic shore of Canada.