October 5th is most common birthday in U.SA
May 22 least common
“A recent in depth database query conducted by Anybirthday.com suggests that October 5th is the United States most popular birth date. It seems that on average more people are born on this day than any other.
“According to the inquiry, an average of 12,576 people are born each year on the 5th of October. It also suggests that some 968,000 Americans celebrate this day annually.
“What makes this early October birth date so fashionable? October 5th however held a not-so-suprising significance, as conception would have fallen right on New Years Eve.
“Which birth date is the least common? May 22nd with an average of 10,259 persons born each year.” Source