Housing here skews old: 62.7% predates 1980 against a national 49.7%. Those 3,643,783 households renovate rather than rebuild, and renovation is the single most reliable generator of hauling work.
Chicago has 3,643,783 households across a population of 9,371,595. Junk removal demand tracks households more closely than anything else: people move, renovate, downsize and clear out, and every one of those is a job for someone with a truck and a crew.
Where these figures come from
Every number in these paragraphs is a Census figure for the Chicago metro, compared with the national figure from the same table.