These days the decline in Great Lakes shipping volumes is often framed as an inevitability, but there are some underlying assumptions there that we can re-examine. When we do so, we may realize that Lakes shipping's stagnation/decline is an intentional policy decision more than an unchangeable destiny.
Each year millions of tons of heavy/dense/high flow-volume cargo moves between Great Lakes port cities by land transportation, mostly long-haul freight truck. This is not because trucks are more fuel or labor efficient over the long haul, quite the opposite. Instead, this is because transportation and energy policy over the past 5+ decades have aimed massive direct and indirect taxpayer-funded subsidies to un-balance the transportation system away from fuel and labor saving modes (marine) and toward less efficient, more high-maintenance (and not to mention more dangerous) ones.
It is almost unbelievable that trucks carry hundreds of thousands of tons
per week of iron and steel, scrap metal, machinery, rubber and plastics, paper products, etc. long distances between Great Lakes cities that happen to have expansive, under-utilized port facilities. Here's what analysts discovered when they examined the flow of cargo in and out of just one major Great Lakes metropolitan area:
https://www.hopaports.ca/wp-content/upl ... -FINAL.pdf - those kind of cargo flows, if re-directed to ships, would mean dozens more ships plying a number of trades on the Lakes.
If policy and subsidies were reformed to make the playing field level again, or even to encourage more efficient transport modes for a given cargo flow, we'd likely witness a major revival in Great Lakes shipping especially in the "general cargo" trades. The more heavy/high-volume cargo that moves by water vs. long-haul truck, the less expensive highway maintenance becomes, since heavy trucks create the majority of highway wear and tear, which taxpayers presently subsidize a significant portions of the cost for fixing. The more cargo moves by water vs. long-haul truck, the safer driving becomes for civilians, since mixing passenger cars with long-haul freight trucks on roads creates dangerous situations as we might know all too well. The more long-haul freight moves by water vs. trucks, the more the labor shortage in truck-driving can be eased, and the more truck drivers can focus on working the "last mile" sort of routes where trucking shines, i.e. moving goods where railroads or ships and barges can't reach.
A nice bonus to a major revival in Great Lakes shipping would be the return of the kind of boat-watching scene one might've enjoyed in the 1920s - 1970s. Imagine a parade of dozens more lakers carrying general cargo, agricultural goods, freight ferry traffic, etc. joining the present-day amounts of iron ore, coal, and stone traffic past, say, Port Huron, Port Colborne, and on waterfront towns and cities all around the region. It's not much of a pipe dream to think about this possibility; if the Great Lakes region were its own nation it would rank among the largest economies in the world. That cargo is already there, it's already moving, except right now it's in that 50' trailer stuck in weekend vacation traffic with you on the freeway vs. gliding past a waterfront park on the St. Clair river.