Before you guess, some explanation of the question is in order. By "distinctive" last name, I mean those that occur most often compared to the nation as a whole. Got it? Okay, make your guess--but think "Swedish" while you're doing it.

Credit for figuring out the most distinctive last names in Illinois (and the nation as a whole) goes to Vice columnist, and MentalFloss contributor, Simon Davis.

According to Chicagoist:

To determine the most distinctive surname, Davis used Social Security Administration data to find “the difference between the state and national prevalence of each of the top 250 last names nationwide.”

One clue before you guess and/or read on: the most distinctive last name in Illinois has nearly 700 entries in the Rockford phone book. It's also the real last name of a famous local drummer named "Bun."

You've got it? If you said "Carlson," you deserve some congratulations. It turns out the 5 most distinctive last names in Illinois draw from Scandinavian or German descent.

Here's Illinois' top 5 most distinctive last names:

1) Carlson
2) Schultz
3) Larson
4) Meyer
5) Becker

In Wisconsin, it's "Schultz."

In Minnesota, it's "Olson."

In Iowa, it's "Hansen."

In Missouri, it's "Meyer."

In Indiana, it's "Myers."

In Michigan, it's "Schultz."

As Chicagoist points out:

The full nationwide map is fascinating. For example, Illinois shares Carlson as winner with another state, but it’s all the way across the country, in Connecticut. Other states that share a distinctive name tend to cluster, such as the western stranglehold of Jensen, which spans Oregon, Idaho, Nevada, Utah, Wyoming, and Nebraska. (In fact, given that so many states share a “most distinctive” winner, perhaps “by region” is the more appropriate phrasing than “by state.”) To that end, it's hardly surprising that German and Scandinavian names should heavily impact Illinois' makeup. But given the high levels of immigration from those areas to so many Midwest states, beginning around the 1800s, it's a bit surprising to see the names stand as so "distinctive."