He experimented by moving dressed (cut) meat using a string of ten boxcars which ran with their doors removed, and made a few test shipments to New York City during the winter months over the Grand Trunk Railway (GTR).
The meat was packed tightly at the bottom of the car to keep the center of gravity low and to prevent the cargo from shifting.
Swift's attempts to sell this design to the major railroads were unanimously rebuffed as the companies feared that they would jeopardize their considerable investments in stock cars and animal pens if refrigerated meat transport gained wide acceptance.
In response, Swift financed the initial production run on his own, then — when the American roads refused his business — he contracted with the Grand Trunk Railway (who derived little income from transporting animals "on-the-hoof") to haul them into Michigan and then eastward through Canada.
Within a year the Line’s roster had risen to nearly 200 units, and Swift was transporting an average of 3,000 carcasses a week to Boston.