There was a collector named James Armstong who lived in New Jersey, and he actively collected signed baseballs most of them single signed from around 1930-1950. He died in the 1960's and his family sold His collection which was so massive it required a pair of big rigg tractor trailors to transport it.
A news article was written before his death and he claimed to own something like 250,000 signed baseballs in addition to rooms full of other autographed items and memorabilia . Much of what he had still turns up on the market today.
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jim@stinsonsports.com