With all the headlines on trade disruptions, you might have expected U.S. imports to fall in December. They didn’t, according to new data from Descartes.

The U.S. imported 2,107,012 twenty-foot equivalent units of containerized goods in December, up 0.4% from November and up 9.2% year on year, said Descartes (NYSE: DSGX) on Monday.

December is traditionally slow from a seasonal perspective — and there was another headwind this year.

A drought in Panama significantly reduced transits of larger Neopanamax-class container ships in November and December, with transit constraints intensifying last month.

Container vessels that traditionally used the Panama Canal to bring Asian goods to East and Gulf Coast ports switched to the Suez Canal. Those ships then rerouted from the Suez Canal to longer voyages around the Cape of Good Hope, with diversions starting in late November and accelerating in recent weeks.

Intuitively, this should have led to some pressure on U.S. import volumes in December, with weakness centered on East and Gulf Coast ports, as had been the case in November.