Main form of transportation was foot, in the form of a coffle. This refers to a specific notoriously cruel practice in the US of a group of slaves walking on foot, connected to each other with rigid metal beams that they were physically trapped in, wrapped around their necks and then shut with a metal bolt that couldn't physically be removed, even by the slave driver, until the destination was reached and a skilled blacksmith could use tools to get it off. You can see images if you google "coffle". Hands were in chains as well so they couldn't use them for eating or cleaning themselves. While the men were bolted together this way, women and children might be tied together with rope and follow behind the men. The pace they were forced to keep to was fast and exhausting. It was especially uncomfortable if a man was significantly taller or shorter than average. They were usually barefoot, and not fed a lot. No rest for injury, either. Sleepers couldn't lie down, but had to sleep in the coffle. Once they reached their destination, they were released from the chains and fattened up again and left to heal from their injuries so they would be more saleable.

If you'd like to read more, check out the beginning of the book The Half Has Never Been Told.