Something as straightforward as a rocking chair is maybe hard to precisely date: there may have been some craftsman in the three thousand-plus years in which chairs were used who stuck rockers on one. But the first successful popular design would be that of the Shakers, who began manufacturing them in large numbers with their famous ladder-back chairs in their Mt Lebanon NY community in the 1870's, and sold them across the US. How widespread they've become around the world perhaps someone else will know.

Hornung:Treasury of American Design and Antiques