What was the most common birthday in 2009?

Published by Birthday Traffic · September 15, 2026 · Sources and method

September 9most births in 2009a Wednesday, 16,081 births
December 25fewest births in 2009a Friday, 6,160 births
Septemberbusiest month per day12,256 births per day
Tuesdaybusiest weekday13,559 per day against 7,380 on Sunday

In 2009 the United States recorded 4,190,991 births over 365 days, 11,482 on an average day. The busiest single date was September 9, a Wednesday, with 16,081 births; the quietest was December 25, a Friday, with 6,160. Within one year every date has one weekday, so the weekday column below is a fact of that date.

Every day of 2009: recorded U.S. births

Every day of 2009 in calendar order as one line, with the busiest and quietest dates marked and the year’s average day drawn across it.

The regular dips are weekends. The deepest dips are fixed holidays.

The busiest dates of 2009

Dates of 2009 with the most recorded U.S. births
Date	Weekday	Births	% of an average day
September 9	Wednesday	16,081	140.1
September 10	Thursday	14,887	129.7
December 29	Tuesday	14,600	127.2
September 15	Tuesday	14,558	126.8
May 27	Wednesday	14,350	125.0
September 22	Tuesday	14,318	124.7
July 1	Wednesday	14,311	124.6
July 8	Wednesday	14,252	124.1
August 18	Tuesday	14,226	123.9
July 7	Tuesday	14,208	123.7

The quietest dates of 2009

Dates of 2009 with the fewest recorded U.S. births
Date	Weekday	Births	% of an average day
December 25	Friday	6,160	53.6
November 26	Thursday	6,864	59.8
April 12	Sunday	6,864	59.8
December 13	Sunday	7,027	61.2
December 6	Sunday	7,103	61.9
October 25	Sunday	7,120	62.0
January 11	Sunday	7,122	62.0
March 15	Sunday	7,130	62.1
January 18	Sunday	7,151	62.3
March 22	Sunday	7,168	62.4

2009 by weekday and by month

Weekend days in 2009 recorded 61% of a weekday’s births per day. The quietest dates above are mostly weekend days and fixed holidays; the busiest are weekdays in late summer. The counts show the association.

2009: births per day by weekday

Seven columns, Monday to Sunday, average recorded births per day in 2009.

2009: births per day by weekday
Weekday	Days	Births per day
Tuesday	52	13,559
Wednesday	52	13,254
Thursday	53	12,946
Friday	52	12,545
Monday	52	12,258
Saturday	52	8,405
Sunday	52	7,380

2009: births per day by month
Month	Births	Births per day
September	367,694	12,256
July	373,491	12,048
August	364,795	11,768
June	351,620	11,721
February	321,122	11,469
April	341,822	11,394
October	353,059	11,389
March	352,571	11,373
May	349,831	11,285
December	346,764	11,186
January	342,975	11,064
November	325,247	10,842

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Sources, method and limits

Source for 2009: Social Security Administration daily births for the United States, as compiled by FiveThirtyEight (CC BY 4.0). The 2000–2003 overlap between the two files is taken from the SSA file only. Weekday is taken from the record’s calendar date. Ranks within a year compare single days.

Every figure above comes from the administrative records named here, at the granularity those records publish: a day, a month or a year. Coverage and definitions differ between countries and eras, so two sources are combined only where their documentation states the windows are separate, and the page where that happens says so.

Full method, leap-day treatment and definitions.

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