 lamar county is a county located in the u.s. state of georgia. as of the 2010 census, the population was 18,317. the county seat is barnesville. lamar county is included in the atlanta-sandy springs-roswell, ga metropolitan statistical area. ==history== the georgia general assembly proposed the constitutional amendment to create the county on august 17, 1920, and the citizens of the state voted in favor of the amendment on november 2, 1920.georgiainfo - carl vinson institute of government land from pike county and monroe county was then transferred to create lamar county. lamar county was named after lucius quintus cincinnatus lamar ii. ==geography== according to the u.s. census bureau, the county has a total area of , of which  is land and  (1.3%) is water. ===major highways===  * 20px interstate 75 * 20px u.s. route 41 * 25px u.s. route 341 * 20px state route 7 * 20px state route 18 * 20px state route 36 * 20px state route 109 * 20px state route 401 (unsigned designation for i-75)  ===adjacent counties=== *butts county (northeast) *monroe county (east) *upson county (southwest) *[[pike count
1920_establishments_in_Georgia_(U.S._state) Atlanta_metropolitan_area_counties Georgia_(U.S._state)_counties Lamar_County,_Georgia Populated_places_established_in_1920