the Mason-Dixon Line
noun /ðə ˌmeɪsn ˈdɪksn laɪn/
/ðə ˌmeɪsn ˈdɪksn laɪn/
[singular]- the border between the US states of Maryland and Pennsylvania that is thought of as the dividing line between the south of the US and the north. In the past it formed the northern border of the states where slaves were owned.
梅森–迪克森线(美国马里兰州与宾夕法尼亚州之间的分界线,为过去蓄奴州的最北边界线)