The 1940's was a decade of annexing and construction for District 47. Haligus rural school district was annexed into District 47 in 1946 followed by South Prairie school district in 1947 and Holcombville rural school district in 1949.
In 1948, construction began on Union School and the 1883 portion of the building was removed. In order to house the students after the 1883 building was torn down but before the new school was completed, the District erected temporary buildings (barracks from Camp Grant). The new addition was attached to the remaining 1906 and 1914 portions of the building making the school a single structure. The new school was named Central Elementary and was the first school built by Crystal Lake Community Consolidated School District 47 for $660,000. Central Elementary School's first principal was Leon Lundahl.