“Listen to the Mocking Bird” (1855) was one of Septimus Winner’s most popular songs. Between 1855 and 1905, about 20 million copies of the song were sold.
A 1937 Homage to Winner in Time suggests that the song may have helped popularize a baby name:
Many an ante-bellum baby was named after Hally, the fictitious girl over whom the song moons:
I’m dreaming now of Hally, sweet Hally, sweet Hally,
I’m dreaming now of Hally,
For the thought of her is one that never dies.
She’s sleeping in the valley, the valley, the valley,
She’s sleeping in the valley,
And the mocking bird is singing where
The name is spelled “Hally” in Time and in sheet music from 1856, but spelled “Hallie” in other sources, like Music of the Civil War Era by Steven H. Cornelius. Hallie/Hally is a pet form of Harriet, Henrietta and related names.
I’m not sure what kind of impact “Listen to the Mocking Bird” had on baby names in the mid-1800s, but Hallie was used regularly as a baby name in the late 1800s and early 1900s according to Social Security Administration data. The spelling Hally was rarely used.
P.S. Want to hear the song? Here’s Tom Roush’s version of Listen to the Mocking Bird, via YouTube.