They grow seedless watermelons now and personal size ones. I suspect the real problem is that your area of the country isn't a good melon growing one. Melons need hot days, cool nights, and abundant sunshine. Perhaps melons are imported from Southern states and Mexico into your area but would it be worth it? I would like to see more processed foods from melons so the market could grow more. They've done this with pomegranates. There's pomegranate juice everywhere. You're starting to see watermelon waters, juices, coolers, and syrups. I'd love to be able to buy frozen watermelon concentrate.
No, that's not the case. In season, every farm stand in Lancaster County has home-grown watermelons and mountains and mountains of locally grown cantaloupes. At least before climate change became an issue, hot days, cool nights, and abundant sunshine pretty well describes summer in the farming regions here away from the cities.
Today I went to our Reading Terminal Farmers' Market. It was a real disappointment; I don't expect I'll be shopping there much anymore. The Amishman from whom I used to buy wonderful sweet corn and Beefsteak tomatoes now sells only packaged snack foods. There is just really no place to buy local produce anymore. There is a produce shop, but you have no idea where their vegetables come from. Last summer I got some acceptable sweet corn from them, but it's not the same. The corn and tomatoes and other fresh vegetables the Amishman used to sell came from Lancaster County.
There are still good stands for fresh meats, fish, and poultry, but not for produce anymore.
(Incidentally, the opening A in "Amish" is not a long A. It's pronounced like the A in "Ah-hah!" A lot of tourists get that wrong, or, at any rate, they used to.)