Final answer:
The economic practice and attitude the British took towards the colonies that caused them to ignore what was happening in America for almost 150 years was known as salutary neglect.
Step-by-step explanation:
The economic practice and attitude the British took towards the colonies that caused them to ignore what was happening in America for almost 150 years was known as salutary neglect. This policy, originating in the early 1700s, was a result of British Prime Minister Robert Walpole's belief that less interference in colonial affairs would allow for greater economic growth.
During this period, the British government largely ignored economic development in the American colonies and did not enforce strict regulations, such as the Navigation Acts, which were designed to maximize British profit from the colonies. Consequently, the colonists were able to flourish economically and govern themselves to a large extent.