If Emco was in Bloomington, Illinois, then chances are it was somehow connected to the Eureka Williams Company which was headquartered in that town.
That Eureka canister was known as the Empress II, a more modern and improved version of the famous Empress canister from the late 1960's. It took on the 1800 Series model numbers, with 1820 being the low end, and 1880 being the top of the line. I would date this around 1970.
Eureka used a "sports car" metaphor for marketing this beautiful vac. Trade advertisements called it the "FastVac" and touted it's large "Mag Wheels" for easy movement over all terrain, racing stripes down the sides (yours seems to be rubbed out), "easy on" push pedal designed like a car's accelerator pedal, and even "radio push buttons" on top to adjust the suction. Yours seems to be a middle of the line: The low end version had no suction buttons (1820), and the high end version had 7 buttons (1880).
This was the Eureka canister that came before the boxier "Sweet Sixteen" 1600 series (Ironside, Quiet Kleen, etc.), and the design survived into the 1980's when it was enhanced by a power nozzle to become a deluxe Roto Matic Power Team canister vac. Store brand versions of this include Eaton Viking in Canada, and JCPenney and Wards in the USA. Not sure if there ever was a commercial Sanitaire version though.
Love the fact it came with all those duplicate Eureka attachments!
