What hints are given in Section 1 that "A Rose for Emily" takes place in the South?

There are other hints, too, in Section I. For example, the mayor, Colonel Sartoris, "fathered the edict that no Negro woman should appear on the streets without an apron (288), and also a reference to the graves of Union and Confederate soldiers. 

Additionally, all of Miss Emily's servants are "Negro," and in the North, servants were less likely to be so.  The prevalence of African-American servants in the South was largely a function of the aftermath of the Civil War and the freeing of slaves, who seldom had the financial wherewithal to leave the areas in which they had been slaves.  Many former slaves stayed with the plantations on which they had been enslaved, continuing to be field workers or house servants.