Every year for the last 10 years, 89-year-old Phil Hull has rolled out his antique tractor collection for the Fourth of July.

It's a photo of the last tractor produced at the International Harvester Farmall Plant in Rock Island, rolling off the final assembly line 30 years ago this week, a model 5488 with all-wheel drive.

Most all of these were gas tractors, but a few used diesel fuel. As the number of farmers declined through the years, and the ...