Mason–Dixon Line
Concise Oxford English Dictionary © 2008 Oxford University Press:
Mason–Dixon Line/meɪs(ə)nˈdɪks(ə)n/
▶noun (in the US) the boundary between Maryland and Pennsylvania, taken as the northern limit of the slave-owning states before the abolition of slavery.
– origin named after Charles Mason and Jeremiah Dixon, who surveyed it in 1763–7.
'Mason–Dixon Line' also found in these Oxford entries:
