Answer
The Port of Montevideo plays a central role in Uruguay’s foreign trade, but it is misleading to state a share of about 80% without specifying the year and measure. Statistics distinguish between the value and physical volume of cargo, containers, transit and national exports; some flows pass through other ports and land crossings.
The port’s importance stems from deep-water access, its container terminal, warehouses and location on the Río de la Plata. It handles both Uruguayan cargo and regional transit, affecting logistics, jobs and the development of Ciudad Vieja.
For an accurate figure, use the latest annual report from the Administración Nacional de Puertos together with foreign-trade data. Check what the denominator covers: all of the country’s trade, maritime trade or a particular category of goods.