Ind. Code § 7.1-1-3-38

Sec. 38. Residential District. The term "residential district" means an area composed of all territory within a radius of five hundred (500) feet of the premises described in the application for a permit being considered and in which area seventy-five percent (75%) or more of the territory in use is used for residential purposes as opposed to commercial, business or manufacturing purposes. Territory in use in the area does not include territory which consists in or is devoted to a street, alley, vacant lot, park, parkway, church, school, religious institution, other not-for-profit institution, lake, river, or other body of water.