Cargo containers at Wando Welch

The State Ports Authority set its third consecutive record for annual containerized cargo growth in 2018. Provided/State Ports Authority

The State Ports Authority saw its third consecutive year of record containerized cargo growth in 2018 with a 6.8 percent increase in boxes moving through its terminals despite tariff concerns.

The Port of Charleston handled the equivalent of 2.3 million 20-foot-long cargo containers last year, the authority said. That beats the previous records set in 2016 and 2017.

The authority also ended the year with its highest-ever December cargo volumes — 199,701 boxes, a 9.2 percent increase over the same month a year ago.

The increases were partly attributed to shippers moving cargo ahead of now-delayed tariffs on Chinese goods that were supposed to take effect Jan. 1. China is the port's biggest trade partner.

"January is already off to a strong start and, despite uncertainty in the trade industry, we are optimistic that volumes will remain strong as we work to achieve our plans for 4.4 percent growth in fiscal 2019," Jim Newsome, the authority's president and CEO, said in a statement.

The authority marked several milestones in 2018, including the start of Charleston Harbor dredging to dig the waterway to 52 feet so big container ships can visit the port at any time regardless of tides.

The SPA also opened another inland port — this one along the U.S. Interstate 95 corridor in Dillon — and finished a modernization of the wharf at Wando Welch Terminal so the Mount Pleasant facility can handle bigger ships and cranes.

Reach David Wren at 843-937-5550 or on Twitter at @David_Wren_