The US is the largest economy in the world.
Economy and consumption come hand in hand.
So it's not that hard to understand that there are multiple retailers in the US. And some of them are big.
But how do we differentiate $Costco (COST.US)$ from $Walmart (WMT.US)$ and $Target (TGT.US)$?
And what is the strength of Costco against its competitors?
1.  Costco uses memberships to build a loyal customer base
Most retailers welcome anyone to sho...