1st was the repeal of the railroad taxes passed during the reconstruction era with protected Northern industry by imposing a tax on goods shipped from the southern states to the north by rail. With that tax eliminated northern industry started moving south because of the better climate and the low wage non unionized work force.
2nd was the invention of the Rust mechanical Cotton Picker which broken the dependence of southern agriculture on large numbers of workers to produce that crop. It became necessary for the southern worker to obtain an education rather than rely on working on the farms.