<page_title> Oak Park, Illinois </page_title> <section_title> Demographics </section_title> <table> <cell> 1940 <col_header> Historical population </col_header> <col_header> Census </col_header> </cell> <cell> 66,015 <col_header> Historical population </col_header> <col_header> Pop. </col_header> </cell> </table>
The population was 66,015 in 1940.