1. Martin Marietta Aggregates 2336 210th St, Humboldt, IA 50548 Coordinate: 42.74607,-94.16883 Phone: (515) 332-1256
2. Fastenal Company 1006 13th St N, Humboldt, IA 50548 Coordinate: 42.73297,-94.22724 Phone: (515) 332-1352