Liquor Store Math

Is it worth driving to Superior from Duluth to save money on off-sale alcohol purchases? Old-fashioned mathematics has the answer, and the short version of it is this: It's only worth it if you're spending more than $45.

There are a number of variables in the equation used to solve this problem. Gas prices change frequently, some vehicles get better mileage than others, distances between homes and liquor stores vary, and people assign different values to their time. So, the magic number of a $45 purchase is really a low-end estimate.

A closer look at the numbers -- a story problem approach, so to speak -- may be useful for examining the accuracy of this figure pertaining to the unique circumstances of any individual. It's also helpful to math teachers who always say "show your work."

Let's say you live in West Duluth and want to buy a 12-pack of Bud Light. (That's who you are, isn't it?) The base price is generally the same. For example, on Memorial Day weekend Liberty Liquor in Duluth and Keyport Liquor in Superior both priced that 12-pack at $9.99.

Minnesota has a 6.5 percent sales tax and another 2.5 percent tax on alcohol sales. Duluth adds an additional 1 percent to the sales tax, bringing the total tax to 10 percent. So your $9.99 12-pack of Bud Light becomes $10.99 in Duluth.

Wisconsin has a 5 percent sales tax, with no extra tax on alcohol. Douglas County adds another 0.5 percent to the sales tax, bringing the total tax to 5.5 percent. So the same $9.99 12-pack of Bud Light becomes $10.54 in Superior.

By crossing the bridge, you saved 45 cents. But if gas is $2.25 per gallon and your car gets 20 miles per gallon -- and your proximity to a Superior liquor store amounts to an extra 8-mile round trip -- the gas amounts to 90 cents. So instead of saving 45 cents, you've lost 45 cents.

Also, an 8-mile round trip to Superior takes about 10 driving minutes. Minnesota's minimum wage is $6.15, so you should make sure you save at least $1 on your alcohol purchase in Superior, on top of the gas cost, before it's worthwhile.

Therefore, the trip to Superior starts to be worthwhile when the purchase reaches a savings of roughly $2 or more. This is achievable with a $45 purchase, which totals $49.50 in Duluth or $47.48 in Superior.

Paul Lundgren is a newspaper columnist and a very nice man. His e-mail address is mail @ paullundgren.com.