Complex sentence: The Port of Calcite located in the city limits of Rogers City continues to be busy, shipping upwards of 300,000 tons of limestone each year or about 500 boatloads.
Split into simpler sentences: The Port of Calcite is located in the city limits of Rogers City. It is a busy port, shipping upwards of 300,000 tons of limestone each year or about 500 boatloads.