During the colonial period in New Jersey, industry began to grow in the Pine Barrens area with the manufacture of iron and glass from local bog iron ores and sands. Commerce was important, and New Jersey's roadways were important because of the state's location between New York and Philadelphia, and between the northern and southern colonies. During the Revolution, both British and Colonial armies marched, occupied, and plundered across the colony. Major battles were fought at Trenton and Monmouth and Washington's army spent two winters at Morristown. Princeton was the capital of the new country for four months in 1783. New Jersey became the third state to ratify the Constitution, on September 11, 1787.