CHICAGO (WLS) -- Chicago mayor Lori Lightfoot will introduce an ordinance Wednesday establishing zoning rules for recreational marijuana sales in the city, including a ban on sales downtown.The mayor said the ordinance will establish seven "cannabis zones" citywide, encompassing the entire geography of the city, and will cap the number dispensaries initially to "ensure an equal distribution of dispensaries across the city.""This ordinance is the first of several regulatory measures to be undertaken by the City of Chicago establish the safe and responsible implementation of legalized cannabis next year," said Mayor Lightfoot.The city is proposing regulations defining distancing requirements, like prohibiting recreational marijuana businesses within 500 feet of a school or in an area zoned as residential.The ordinance also creates an exclusion zone in the city's Central Business District, defined as being bordered by Oak Street to the north, Lake Michigan to the East, Ida B. Wells Drive to the south and LaSalle Drive in River North and the Chicago River in the Loop to the west. Within that exclusion zone, no cannabis sales will be permitted.Existing licensed medical marijuana dispensaries will be permitted to sell recreational marijuana under the ordinance. Recreational marijuana sales and use will be legal for adults over 21 starting on January 1, 2020.Use of recreational marijuana is prohibited in all public places citywide, and by anyone under the age of 21, in accordance with state law.The six other cannabis zones established by the ordinance are:: city limits to the north, Lake Michigan to the east, Division Street to the south and Interstate 90/94 to the west.: Division Street to the north, Lake Michigan to the east, Interstate 55 to the south and Interstate 90/94 to the west.: Interstate 55 to the north, Lake Michigan to the east, 87th Street to the south and Interstate 90/94 to the west.: 87th Street to the north, Lake Michigan to the east and the city limits to the south and west.: Interstate 55 to the north, Interstate 90/94 to the east, 87th Street to the south and the city limits to the west.: Division Street to the north, Interstate 90/94 to the east, Interstate 55 to the south and the city limits to the west.: city limits to the north, Interstate 90/94 to the east, Division Street to the south and the city limits to the west.