If you just said to yourself "I know the top three! It's gotta be Grimsdottir, Wamboldt, and Zeleznik," you might want to take another shot at this.

By the way, those three surnames above came off a list of the least common surnames in America. (thanks to Mongabay.com).

For the most common last names, we turn to a name that, thanks to some serious advertising over the last decade or so, has become pretty much a household name: Ancestry.com.

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I said Illinois last names, not Welsh last names. (Getty Images)
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It Turns Out The Illinois Isn't All That Different Than The Rest Of The Nation When It Comes To The Most Common Last Name

Here in Illinois, the most common last name (or, to be proper, surname) is also the most common last name in the United States: Smith.

Smith, along with JohnsonMillerJonesWilliams, and Anderson make up most of the most common surnames all across the country.

Here in Illinois, our top 3 most common surnames are Smith, Johnson, and Williams.

 

  • In Wisconsin, it's Johnson, Smith, and Anderson.
  • In Iowa, it's Smith, Williams, and Johnson.
  • In Indiana, it's Smith, Miller, and Johnson.
  • In Missouri, it's Smith, Johnson, and Williams.

 

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That's a great look, Bill. (Getty Images)
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And, it looks like your tie is in your coffee. (Getty Images)
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It's Pretty Much The Same Throughout The Country, With A Couple Of Notable Exceptions

As Ancestry.com explains, you'll have to travel to the Southwest portion of the country for some surname variety:

Only the Southwestern portion of the country really has a lot of variety. States like Texas, California, New Mexico, and Arizona — where there are large Latino populations — boast a variety of names like Garcia, Hernandez, Martinez, and Chavez. And then there’s Hawaii, whose three most-common surnames — Lee, Wong and Kim — don’t even appear in the top three anywhere else in the country.

Massachusetts, having a large population of those with Irish ancestry, is the only state in the nation where the surname Sullivan is in the top three.

LOOK: Baby names that are illegal around the world

Stacker scoured hundreds of baby name databases and news releases to curate a list of baby names that are illegal somewhere in the world, along with explanations for why they’re banned.

KEEP READING: What were the most popular baby names from the past 100 years?