A more thorough explanation:

Granger Cases refer to six decisions made by the U.S. Supreme Court in 1876. These cases affirmed the government's right to regulate fees charged by common carriers, warehouses, and grain elevators. The cases arose from farmers' frustration with the high prices they were paying to store and transport their agricultural products. Several state legislatures passed laws regulating the rates, but the affected businesses sued to have the laws overturned. The Court rejected these claims, stating that the activities involved affected the public interest and were therefore subject to the government's regulatory authority.

The Grange was a social, educational, and political organization formed in 1867. It was formally called the National Grange of the Patrons of Husbandry. The Grange informed its members about agriculture-related legislation and proposals and represented farm interests in lobbying the government. The Grange was the foundation of the Granger Movement, a 19th-century political force that protested economic abuses that increased farmers' costs while forcing down prices for agricultural products. Movement followers, called Grangers, controlled several Midwest state legislatures and passed Granger laws that set maximum rates for railroads, warehouses, and elevators. Railroads and other interested parties challenged the constitutionality of these laws in what have become known as the Granger Cases.

For example, if a farmer wanted to transport their crops to a warehouse, the warehouse could charge an exorbitant fee for storage. The Granger Cases affirmed the government's right to regulate these fees, ensuring that farmers were not taken advantage of by businesses seeking to make a profit.