2000
#134,929
National surname rank
Recorded bearers 115
First available Census row
Per 100,000 0.04
Very Rare Last name
Seniw
A surname derived from the Polish word "siennik" meaning a haymaker or hay worker.
According to the 2020 US Census Bureau surname tables, roughly 125 Americans carry the last name Seniw. That puts it at #150,205 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,742,035 residents).
This page is the full Name Census profile for the Seniw 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
125
1 in 2,742,035
Census rank
#150,205
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
109
very rare in the US
Popularity narrative
The Census Bureau recorded 109 bearers of the surname Seniw in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 150205th position in the national surname ranking.
Among Census respondents with the surname Seniw, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (2.8%).
Origin
Meaning and origin of Seniw
The surname SENIW originated in England during the late medieval period, around the 13th or 14th century. It is believed to have derived from an Old English word "senian," which meant "to send" or "to dispatch." This suggests that the name may have been initially given to a messenger or courier.
One of the earliest recorded instances of the SENIW surname can be found in the Hundred Rolls of Yorkshire, a census-like record from 1273-1274. The entry mentions a "John le Seniw" residing in the village of Bingley.
In the 15th century, the surname appeared in various spellings such as "Senyew," "Seniow," and "Seniew" in different parts of England, particularly in the northern counties of Yorkshire and Lancashire. These variations likely stemmed from regional dialects and inconsistent spelling practices of the time.
During the Tudor period, a notable figure bearing the SENIW name was Sir William Seniw (c. 1490-1558), a wealthy landowner and member of the gentry in Nottinghamshire. He served as a Justice of the Peace and was known for his involvement in local governance.
Another notable SENIW was Robert Seniw (1612-1692), a Puritan minister and theologian from Derbyshire. He was a prominent figure during the English Civil War and served as a chaplain in the Parliamentarian army.
In the 18th century, the SENIW surname was found in various parts of England, including the village of Seniw near Gloucester, which may have been named after an early bearer of the surname.
One of the earliest recorded instances of the SENIW surname in the American colonies can be traced back to William Seniw (1705-1783), a merchant from Essex, England, who settled in Boston, Massachusetts, in the 1730s.
Another notable SENIW was John Seniw (1760-1842), a British naval officer who served during the Napoleonic Wars and was awarded the Naval General Service Medal for his distinguished service.
Throughout its history, the SENIW surname has been associated with various occupations and social classes, from landowners and clergymen to merchants and military personnel, reflecting the diverse backgrounds of its bearers.
Demographics
Ancestry and ethnicity for Seniw
Among Census respondents with the surname Seniw, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (2.8%).
The bar chart below shows how Seniw 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 Seniw surname at the time of the 2020 Census, not any inherent property of the name itself.
- White91.7% · 100
- Hispanic or Latino3.7% · 4
- Two or more races2.8% · 3
- American Indian and Alaska Native1.8% · 2
Timeline
Historical Census data for Seniw
Seniw 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
#147,253
National surname rank
Recorded bearers 112
-3 bearers (-2.6%)
Per 100,000 0.04
Rank movement Down 12,324 places
2020
#150,205
National surname rank
Recorded bearers 109
-3 bearers (-2.7%)
Per 100,000 0.04
Rank movement Down 2,952 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #134,929 | 115 | 0.04 | First available Census row | First available Census row |
| 2010 | #147,253 | 112 | 0.04 | -3 bearers (-2.6%) | Down 12,324 places |
| 2020 | #150,205 | 109 | 0.04 | -3 bearers (-2.7%) | Down 2,952 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 Seniw 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 | #147,253 | #150,205 | -2.0% |
| Count | 112 | 109 | -2.7% |
| Per 100K | 0.04 | 0.04 | -8.8% |
Between the 2010 and 2020 Census, the number of Seniw bearers went from 112 to 109 (-2.7% change). The surname moved down 2,952 positions in the national ranking, going from #147,253 to #150,205.
FAQ
Seniw surname: questions and answers
How many people in the U.S. have the surname Seniw?
Name Census estimates that about 125 living Americans carry the surname Seniw. Using the current population baseline, that works out to roughly 1 in 2,742,035 residents.
How common is Seniw?
Seniw ranks #150,205 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.04 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 109 people with the surname Seniw. That is different from the site's living-bearer estimate (125), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.04 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.04 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 Seniw.
Has Seniw become more or less common over time?
Between 2010 and 2020, the surname Seniw went from 112 recorded bearers to 109. That is a decrease of 3 (-2.7%). In the national ranking it fell from #147,253 to #150,205.
What does the Census say about the background of Seniw?
Among Census respondents with the surname Seniw, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (2.8%). 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 Seniw in the 2020 Census, accounting for 91.7% (100 people in the source table).
What is the full ancestry breakdown?
Seniw appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (91.7%), Hispanic (3.7%), Two or More Races (2.8%). 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 Seniw (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 Seniw mean?
A surname derived from the Polish word "siennik" meaning a haymaker or hay worker. 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 Seniw (0.04 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 have the surname Seniw?
For a faster, more casual read, check HowManyOfMe.org — our sister site built around that single question.