You've pointed out that the DEA's conclusion contradicted its data - which impugns only the DEA's ability to draw conclusions, not its data.
Drug usage was *NOT* declining, it was going up after the civil war.
So you keep claiming although the only available numbers say the opposite.
The 400,000 addict number comes from perscriptions written by Union and Confederate doctors regarding the dispensation of painkillers. This addiction later became known as "the soldier's disease."
You don't have any good numbers, but you have to be a special class of fool to believe that cocaine laced carbonated beverages (Coca-Cola) would not cause deep and widespread addiction.