In the United States, despite tomatoes biologically being fruits, they are federally designated as vegetables. This classification originates from the 1893 United States Supreme Court case Nix vs. Hedden, where the court was tasked with determining the tomato's classification in the context of trade and tariffs. The dispute arose when John Nix, a New York-based wholesaler, imported tomatoes from the West Indies and faced a 10-percent tariff imposed on vegetables. Nix contended that tomatoes, being fruits botanically, should not incur the vegetable tariff.
The Supreme Court, after reviewing definitions and the common usage in trade and culinary contexts, ruled that tomatoes are vegetables. Justice Horace Gray highlighted that tomatoes, along with cucumbers, squashes, beans, and peas, are typically consumed as part of the main meal rather than as a dessert, aligning them with vegetables' culinary role. This legal determination underscored the distinction between botanical and culinary classifications, leading to tomatoes being officially taxed as vegetables in the United States.
Source: wegotthiscovered.com