Sealtest had milk and ice cream plants across the midwestern and northeastern part of the United States, with large operations in Chicago, Milwaukee, Cleveland, La Crosse, Wisconsin, Huntington, Indiana, Rockford, Illinois, Philadelphia, Baltimore and New York City.

[citation needed] Sealtest was one of the brands Martin Luther King Jr. urged people to boycott in the last speech he delivered before his assassination, "I've Been to the Mountaintop": Go out and tell your neighbors not to buy Coca-Cola in Memphis.

[1][2] Sealtest milk products are currently produced and packaged by Milkco, Inc. of Asheville, North Carolina, a subsidiary of Ingles.

[6] In 1981, Ault Foods of Toronto, Ontario acquired Dominion Dairies, and with it the licensing rights to the Sealtest brand name.

At the time, the Sealtest name was used on dairy products including milk and the Parlour brand of ice cream, primarily in Ontario and Quebec.