Cairo ( KAIR-oh) is a village in Allen County, Ohio, United States. As of the 2010 census it had a population of 524. It is included in the Lima Metropolitan Statistical Area.
Cairo was originally called West Cairo, and under the latter name was platted in 1848. A post office called West Cairo was established in 1852, and the name was changed to Cairo in 1922.
Cairo is located at the intersection of what was the east-west U.S. Route 30 (the Lincoln Highway) and the north-south State Route 65 ("Ottawa Road") in the middle of farming country. In the 1970s, Route 30 was upgraded and moved approximately one mile south of Cairo. Now, the east-west street in Cairo is Main Street. Cairo lies near the following city and towns:
The elevation of the land area of Cairo (ranges from about 812' at the west end to 842' at the east end of the village above sea level) is benchmarked at 815 feet (248 m) above sea level, generally flat and moderately wooded. The nearest stream with year-round flow is Rattlesnake Creek, which flows from south of the village and passes just to the west of the village. Water flow in the village is generally from the south and east to the north and west.