 eureka township is a charter township of montcalm county in the u.s. state of michigan. the population was 3,271 at the 2000 census. the city of greenville is within the township, and the greenville post office, with zip code 48838, also serves all of eureka township.zcta reference map for 48838, u.s. census bureau, 2000 census eureka township was established in 1850.walter romig, michigan place names, p. 188 ==geography== according to the united states census bureau, the township has a total area of , of which  is land and  (2.34%) is water. ==demographics== as of the [[ce
1850_establishments_in_Michigan Charter_townships_in_Michigan Townships_in_Montcalm_County,_Michigan