Subjects
- Leisure--Michigan.1
- Lifeguards.1
- Lighthouses.1
- Lightships.1
- Loading docks.1
- Loggers--Michigan.1
- Logging railroads.1
- Logging--Michigan.1
- Lumber camps--Michigan.1
- Lumbering.1
- Lumbermen.1
- Machine shops.1
- Machinery.1
- Manufacturing.1
- Masonry.1
- Metallurgical industry.1
- Metalwork.1
- Mineral industries.1
- Mines.1
- Mining machinery.1