Green’s Dictionary of Slang

across n.

[abbr. across the Atlantic]

(US) Great Britain.

[US]H. Green Actors’ Boarding House (1906) 81: When I was across, I heard her sing.
[US]A.W. Scherr diary 23 Dec. [Internet] What at first seemed an authentic, had it that this was day to leave Camp MacArthur for ‘across’.