Fishing, the state's earliest industry, has declined considerably, although lobsters are still caught in abundance. The proximity of harbors to forests early encouraged shipbuilding, which reached its peak in the 19th cent. With the disappearance of wooden ships and the related timber trade, commercial activity slackened. Portland, the largest port, now operates far below its substantial capacity, handling chiefly oil for the pipeline to Montreal. Bath Iron Works, which builds warships, remains the state's largest single-site employer.
Manufacturing is still the largest sector in the state's economy.
Maine is a leading producer of paper and wood products, which are the most valuable of all manufactures in the state. The mineral wealth of the state is considerable. Many varieties of granite, including some superior ornamental types, have been used for construction throughout the nation. Sand and gravel, zinc, and peat are found in addition to stone. However, much of Maine's abundant natural and industrial resources remain undeveloped.