2000
#33,292
National surname rank
Recorded bearers 647
First available Census row
Per 100,000 0.24
Very Rare Last name
Mroczkowski
A Polish locational surname referring to someone from a misty or foggy place.
According to the 2020 US Census Bureau surname tables, roughly 702 Americans carry the last name Mroczkowski. That puts it at #38,883 in the national surname ranking, appearing at a frequency of 0.20 per 100,000 people (about 1 in 488,254 residents).
This page is the full Name Census profile for the Mroczkowski surname. You will find the Census Bureau frequency data, a multi-census history view, an ancestry and ethnicity breakdown based on self-reported demographics, the name's meaning and origin where available, and answers to the most common questions people ask about this surname.
Bearers in the US
702
1 in 488,254
Census rank
#38,883
2020 decennial data
Per 100,000
0.2
Frequency rate
Recorded bearers
612
very rare in the US
Popularity narrative
The Census Bureau recorded 612 bearers of the surname Mroczkowski in its 2020 decennial surname file. At a rate of 0.20 per 100,000 residents, it holds the 38883rd position in the national surname ranking.
Among Census respondents with the surname Mroczkowski, the largest self-reported group is White at 90.2%. The next largest groups are Hispanic (6.0%) and Two or More Races (2.0%).
Origin
Meaning and origin of Mroczkowski
The surname MROCZKOWSKI originated in Poland during the medieval period. It is derived from the Polish word "mroczny," meaning "dark" or "gloomy." This suggests that the name may have been initially given as a descriptive nickname for someone with a dark complexion or somber demeanor.
The earliest known record of the MROCZKOWSKI surname dates back to the late 15th century in the city of Krakow, where a certain Jan Mroczkowski is mentioned in a municipal registry from 1492. It's likely that the name was already in use among Polish families for some time before this first written record.
In the 16th century, the MROCZKOWSKI name appeared in various historical documents and records across various regions of Poland, particularly in the areas around Krakow, Warsaw, and Poznan. Some variations in spelling, such as "Mroczkowsky" and "Mroczkovski," were also noted during this period.
One notable figure bearing the MROCZKOWSKI surname was Andrzej Mroczkowski, a Polish nobleman and military commander who served under King Stefan Batory in the late 16th century. He played a significant role in the Polish-Muscovite War from 1577 to 1582.
Another prominent individual was Franciszek Mroczkowski (1768-1840), a Polish writer, poet, and translator who was active during the Enlightenment era. He is best known for his translations of works by Voltaire and other French authors into Polish.
In the 19th century, the MROCZKOWSKI name gained further recognition with Jan Mroczkowski (1805-1871), a Polish engineer and architect who designed several notable buildings in Warsaw, including the Church of the Holy Cross and the Great Theater.
Towards the end of the 19th century, Stanisław Mroczkowski (1853-1928) made significant contributions to the field of Polish linguistics and philology. He authored numerous works on the history and structure of the Polish language.
It's worth noting that the MROCZKOWSKI surname has also been associated with several place names in Poland, such as the village of Mroczkowice near Krakow and the town of Mroczki in the Masovian Voivodeship.
Demographics
Ancestry and ethnicity for Mroczkowski
Among Census respondents with the surname Mroczkowski, the largest self-reported group is White at 90.2%. The next largest groups are Hispanic (6.0%) and Two or More Races (2.0%).
The bar chart below shows how Mroczkowski bearers described their own race and ethnicity on the 2020 Census form. The Census Bureau groups responses into six broad categories: White, Black or African American, Hispanic or Latino, Asian and Pacific Islander, American Indian and Alaska Native, and Two or More Races. When a category has too few respondents for a given surname, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown for every Census year so the breakdown stays comparable over time. When the source file also includes raw headcounts, Name Census shows those alongside the percentages in the legend.
Keep in mind that these are self-reported numbers. A person's surname does not determine their race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the Mroczkowski surname at the time of the 2020 Census, not any inherent property of the name itself.
- White90.2% · 552
- Hispanic or Latino6.0% · 37
- Two or more races2.0% · 12
- Asian and Pacific Islander0.8% · 5
- Black or African American0.7% · 4
- American Indian and Alaska Native0.3% · 2
Timeline
Historical Census data for Mroczkowski
Mroczkowski appears in 3 published Census surname files: 2000, 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2010
#35,447
National surname rank
Recorded bearers 635
-12 bearers (-1.9%)
Per 100,000 0.22
Rank movement Down 2,155 places
2020
#38,883
National surname rank
Recorded bearers 612
-23 bearers (-3.6%)
Per 100,000 0.20
Rank movement Down 3,436 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #33,292 | 647 | 0.24 | First available Census row | First available Census row |
| 2010 | #35,447 | 635 | 0.22 | -12 bearers (-1.9%) | Down 2,155 places |
| 2020 | #38,883 | 612 | 0.20 | -23 bearers (-3.6%) | Down 3,436 places |
For 2020, the Census Bureau published race and Hispanic-origin columns as counts rather than percentages. Name Census converts those counts back into shares so the ancestry section stays comparable with the older surname files.
Year on year
2010 vs 2020 Census
How has the Mroczkowski surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
20102020
| Metric | 2010 | 2020 | Change |
|---|---|---|---|
| Rank | #35,447 | #38,883 | -9.7% |
| Count | 635 | 612 | -3.6% |
| Per 100K | 0.22 | 0.20 | -6.9% |
Between the 2010 and 2020 Census, the number of Mroczkowski bearers went from 635 to 612 (-3.6% change). The surname moved down 3,436 positions in the national ranking, going from #35,447 to #38,883.
FAQ
Mroczkowski surname: questions and answers
How many people in the U.S. have the surname Mroczkowski?
Name Census estimates that about 702 living Americans carry the surname Mroczkowski. Using the current population baseline, that works out to roughly 1 in 488,254 residents.
How common is Mroczkowski?
Mroczkowski ranks #38,883 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.20 per 100,000 residents, which is about 0 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 612 people with the surname Mroczkowski. That is different from the site's living-bearer estimate (702), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.2 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.20 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 0 of them to have the surname Mroczkowski.
Has Mroczkowski become more or less common over time?
Between 2010 and 2020, the surname Mroczkowski went from 635 recorded bearers to 612. That is a decrease of 23 (-3.6%). In the national ranking it fell from #35,447 to #38,883.
What does the Census say about the background of Mroczkowski?
Among Census respondents with the surname Mroczkowski, the largest self-reported group is White at 90.2%. The next largest groups are Hispanic (6.0%) and Two or More Races (2.0%). These figures come from the 2020 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Which group reports this surname most often?
White is the largest self-reported group for the surname Mroczkowski in the 2020 Census, accounting for 90.2% (552 people in the source table).
What is the full ancestry breakdown?
Mroczkowski appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (90.2%), Hispanic (6.0%), Two or More Races (2.0%). For 2020, the source file also published raw headcounts for each group, which is why this page can show both percentages and counts in the ancestry section.
Is this page using the latest Census data?
Yes. This page is using the latest surname file currently loaded on Name Census, which is 2020. The historical section above also keeps any older Census surname entries we have for Mroczkowski (2000, 2010, 2020).
Does the Census include every surname?
No. The Census Bureau only publishes surnames that appeared at least 100 times in a given decennial Census. That means very rare surnames are excluded entirely, and a surname can appear in one Census release but disappear from a later one if it falls below the reporting threshold.
Why don't the ancestry percentages always add up to exactly 100%?
There are two main reasons: rounding and suppression. The Census Bureau rounds published values, and it may suppress very small cells to protect privacy. For 2020, the Bureau also published raw group counts rather than direct percentages, so Name Census converts those counts back into shares for comparability across census years.
What does Mroczkowski mean?
A Polish locational surname referring to someone from a misty or foggy place. The fuller origin note on this page goes into more detail.
Where does the surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These files list every surname that appeared 100 or more times in the 2020 Census, along with a count, a per-100,000 rate, and a self-reported demographic breakdown. You can read the full explanation on our methodology page.
How does Name Census estimate living bearers?
For surnames, Name Census does not age cohorts the way it does for first names. Instead, it takes the Census Bureau's published frequency for Mroczkowski (0.20 per 100,000) and applies that rate to the current U.S. resident population to estimate how many living Americans have the surname today.
How many people are called Mroczkowski?
If you just want to know how many people have the last name Mroczkowski, HowManyOfMe.org gives you the headline number in one glance.