Though the expression “sold down the river” is now used with wryful humor, as of a baseball player whose contract is sold to a team of lower rating or of an employee who is transferred to a more humble position than he formerly held, there was a time when it was literal and tragic, when it was used in connection with the domestic slave trade of the southern states.
The importation of slaves into the United States was illegal after 1808 (though undoubtedly many thousands were smuggled into the country during the following years) and it then became profitable to build up a domestic trade.
Hence, because cotton and sugar plantations of the South and Southwest were expanding by leaps and bounds, slaves from the worn-out tobacco belt of the upper South were readily purchased from their masters by dealers and were then transported down the Mississippi River to the markets at Natchez or New Orleans.
Regrettably, many dealers regarded slaves to be as insensitive as cattle, so “sold down the river” meant the loss of all ties, the breaking up of families, and, usually, transportation into the most exhausting of labor under notoriously severe and brutal masters.