Before this season, pheasant hunting was only allowed in the Northern half of the state, along with a portion of Southeast Missouri.
According to the department, expanding pheasant hunting across Missouri simplifies rules for hunters without hurting the state's pheasant population.
"Hens are protected from harvest and one rooster often mates with multiple hens," Conservation Department Resource Scientist Beth Emmerich said. "Our rooster-only hunting season has very little impact on overall population size and growth."
However, not all areas of Missouri have pheasant populations and Emmerich said the hunting expansion "does not imply that birds can be harvested or even observed in all areas of the state."
Previously, pheasant hunting in Missouri had limited to what the department called a North Zone consisting of all counties north of Interstate 70 and a portion of St. Charles County south of I-70.
The Southeastern portion of Missouri that allowed pheasant hunting was comprised of Dunklin, New Madrid, Pemiscot and Stoddard counties.
Missouri's pheasant hunting season starts Nov. 1, 2015 and ends Jan. 15, 2016.