Well, as Port Colborne is at the south end of the Welland Canal it most certainly connected to the next destination of the vessel.
Up means taking the locks up to the Great Lakes (Erie, Huron, Michigan and Superior) where the water level is higher. Down means transitting the Welland Canal and locks down towards Lake Ontario to the St. Lawrence and into the North Atlantic.
The expression 'cleared' seems to be in opposite to the term 'arrived' and would mean 'sailings' in that newspaper clip nevertheless the up or down destination.
Brgds, Manfred