Wagons and Carts
Pulling a wagon and it's load costs a fifth of the weight compared to carrying it, but this rule only applies to animals. (Source: PHB)
A cart can be pulled by one animal normally, a wagon by two. (Source: some rando's house rule.)
A chariot by two, a carriage or sled by four. (Source: Sandra's own house rule.)
A rowboat can carry 400 lbs and a keelboat 1000. (Source: Ghosts of Saltmarsh.) So that's something to keep in mind as we try to figure our how much a cart can take. Although carts can't sink.
When carries by normal animals, don't worry about it. "A cart becomes too heavy to pull long before it breaks." But we're gonna need a rule sooner or later in case you have like giants and snakes and stuff pulling your wagons.