For whatever reason, Minnesotans love their checkbooks. They will use them anywhere and everywhere--I've seen people write checks for a $2.37 coffee at Caribou--and when they can't use them, well...
Once, when I was a kid, my mom took me and my brother to Mickey's Diner in St. Paul only to find, when the bill arrived, that they didn't take checks. Like most of the checkbook-reliant (this was BC, before credit cards), Mom never carried more than $10 or so in cash, so she had to leave my brother and I as collateral, duck into a seedy check-cashing store, and then get us back by paying with bill with cash. (Attn: muggers, my mom still never carries more than $20 cash, so don't bother, okay?)
The LA Times is reporting that grocery stores--including Whole Foods--are considering going check-free. Stores that have, in the past, provided limited banking functions--cashing payroll checks, letting customers write larger checks to get cash back with their purchase--will now be asking customers to pay with cash, credit, or debit cards. (Most retailers prefer debit cards that require PINs because they have low transaction fees and more security than cash or checks.)
This may not be a big deal in other parts of the country--I've seen New Yorkers buy $300 worth of groceries with cash--but you may not get a Midwesterner to give up his checkbook unless you're prying it from his cold, dead hands.