What was the most common birthday in 1999?

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

September 9most births in 1999a Thursday, 14,540 births
December 25fewest births in 1999a Saturday, 6,674 births
Septemberbusiest month per day11,647 births per day
Tuesdaybusiest weekday12,424 per day against 7,731 on Sunday

In 1999 the United States recorded 3,959,417 births over 365 days, 10,848 on an average day. The busiest single date was September 9, a Thursday, with 14,540 births; the quietest was December 25, a Saturday, with 6,674. Within one year every date has one weekday, so the weekday column below is a fact of that date.

Every day of 1999: recorded U.S. births

Every day of 1999 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 1999

Dates of 1999 with the most recorded U.S. births
Date	Weekday	Births	% of an average day
September 9	Thursday	14,540	134.0
December 21	Tuesday	13,508	124.5
September 8	Wednesday	13,437	123.9
September 21	Tuesday	13,384	123.4
September 28	Tuesday	13,358	123.1
July 7	Wednesday	13,343	123.0
July 8	Thursday	13,245	122.1
August 17	Tuesday	13,201	121.7
September 10	Friday	13,181	121.5
December 28	Tuesday	13,158	121.3

The quietest dates of 1999

Dates of 1999 with the fewest recorded U.S. births
Date	Weekday	Births	% of an average day
December 25	Saturday	6,674	61.5
April 4	Sunday	7,067	65.1
April 25	Sunday	7,370	67.9
March 28	Sunday	7,389	68.1
April 18	Sunday	7,394	68.2
January 3	Sunday	7,416	68.4
November 28	Sunday	7,418	68.4
December 26	Sunday	7,432	68.5
January 31	Sunday	7,445	68.6
October 24	Sunday	7,465	68.8

1999 by weekday and by month

Weekend days in 1999 recorded 69% 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.

1999: births per day by weekday

Seven columns, Monday to Sunday, average recorded births per day in 1999.

1999: births per day by weekday
Weekday	Days	Births per day
Tuesday	52	12,424
Wednesday	52	12,183
Thursday	52	12,122
Friday	53	11,785
Monday	52	11,018
Saturday	52	8,654
Sunday	52	7,731

1999: births per day by month
Month	Births	Births per day
September	349,409	11,647
August	351,371	11,335
July	349,812	11,284
June	332,201	11,073
December	333,251	10,750
October	332,980	10,741
March	332,939	10,740
February	297,568	10,627
May	328,526	10,598
April	316,889	10,563
November	315,289	10,510
January	319,182	10,296

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Sources, method and limits

Source for 1999: CDC/NCHS daily births for the United States, as compiled by FiveThirtyEight (CC BY 4.0). Years before 2000 come from the CDC/NCHS file; 2000 onward from the SSA file, so a comparison across that line is also a change of source. 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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