Goffin and King gave the Cookies a hit song, but the Cookies gave them a babysitter – and in the early Sixties that was probably just as valuable to the overworked couple with two baby girls. Eva Narcissus Boyd had moved to New York from her native North Carolina with dreams of making it as a singer. She became friendly with the Cookies, auditioning for them by belting Goffin and King's "Will You Love Me Tomorrow." The performance earned her a spot as an "alternate Cookie," occasionally singing backup on their recording dates.
To help Boyd earn some extra income, the Cookies introduced her to Goffin and King, who hired her to look after their daughters Louise and Sherry for $35 a week. "When we were first talking to her about coming to babysit she might have mentioned that she sang in the church choir or something like that," King recalled in a 2003 interview with NPR. "And we said, 'Oh, you sing – cool! Sing something!' And she sang a little something and we thought, 'Oh, this is cool, she's got a really great voice. Make note to self.'"
By 1962, the pop charts had become inundated with an increasingly absurd list of dance-craze songs. Chief among them all was Chubby Checker's monster 1960 hit "The Twist," which trounced the copycat tunes it spawned to make an unprecedented repeat trip to the top of the charts that January. The achievement, unequaled to this day, sent denizens of the Brill Building rushing to their pianos to hammer out the latest dance record.
Goffin and King were no exception. Using Dee Dee Sharp's recent smash, a "Twist" clone called "Mashed Potato Time," as a blueprint, the pair penned a relentless tune called "The Loco-Motion." The original plan was to give the song to Sharp herself, so Boyd was asked to sing the demo version – backed by none other than the Cookies. While it remains unclear whether the song ever actually made its way to Sharp, Dimension Records founder (and music publishing titan) Don Kirshner liked Boyd's version enough to release it as a single under the name Little Eva.
The composers spruced up the demo with some instrumental embroidery, including a striking sax riff overheard at Bobby Darin's Copacabana Club set. "It fit perfectly," Goffin told author Ken Emerson. "We had that drumroll that sounded like an engine and then the horns that sounded like a railroad." The only thing they didn't have was a dance. Instead, they left it for the newly rechristened singer to improvise. "We invented the song and the concept that it would be a train-like movement, but she invented the dance," explains King. "She just did what she thought was the right movement and that became the Loco-Motion."
The song became Goffin and King's third Number One. It would top the charts again for Grand Funk Railroad in 1974, and reach Number Three for Kylie Minogue 14 years later.