From the Lawrence Daily Journal-World for Dec. 21, 1988:

Lawrence Postmaster Bill Reynolds announced today that the city would soon be assigned two additional ZIP codes. The codes, 66047 and 66049, would pertain to areas west of Iowa Street. Reynolds explained that anticipated growth in Lawrence was one of the factors in the decision. “Within each zone, there’s only 9,999 possibilities for ZIP-plus-4 coding,” Reynolds explained. “Growth in the 66044 area had exhausted all those codes…. It’s not something we wanted to do, it’s something we had to do.” Western Lawrence already had land platted with about 1,500 lots that would require new ZIP-plus-4 designations, he said, and the postal service anticipated another 3,000 new addresses within a 10 or 20 year period. Although the codes were not officially going into effect until July 1, 1989, Reynolds suggested that customers in the areas begin using them immediately.