Green’s Dictionary of Slang

(US, Western) tinned foods.

1897		A.H. Lewis Wolfville 330: Air-tights is can peaches, can tomatters, an’ sim’lar bluffs.
1899		W. Archer America To-day 249: I was told of a family which ‘lived on air-tights.’ Their diet consisted of canned (or, as we should say, tinned) provisions.
1907		S.E. White Arizona Nights 219: On top of a few incidental pounds of chile con, baked beans, soda biscuits, ‘air tights’, and other delicacies.
1918		J. Hendryx Texan (2007) 131: ‘The only chance we stand to make a haul is on the air-tights.’ ‘What are air-tights?’ asked the girl. ‘Canned stuff’.
1936		R.F. Adams Cowboy Lingo 148: ‘Airtights’ were canned goods.
1967		R. Flynn North to Yesterday 3: A gray country store [...] dusty shelves packed with air-tights of peaches, apricots, and plums.
1993		(ref. to late 19C) W. Blevins Dict. of the Amer. West 5/1: airtights. canned food [...] Tinned food [...] become in the West in the late 1800s.
1999		(ref. to 1920s) interview on World Without Borders 🌐 GCS Cys: How were the Chuck wagons stocked, or rather what could we expect to find in the average Chuck wagon? Verne Carlson: Potatoes. Lard, Rice. Canned tomatoes (called ‘airtights’). Coffee, meat (usually slaughtered on the trail and wrapped in burlap to keep the flies away.).