Epiphone brand guitars have been made in numerous factories in many locations worldwide, however by far the best instruments (and therefore the most desired) are those made by the the Stathopoulos family in New York in the 1950s, and those made by Gibson in Kalamazoo, MI in the 1960s. Although later Japanese, Korean and Chinese guitars make fine entry, and intermediate level instruments, they do not compete with the classic instruments produced in the USA.
The early story of Epiphone, and it's take-over by Gibson has been told many times, but in short: Epiphone were producing some of the finest archtop guitars in the world, one of Gibson's few rivals. After the death of the main driving force Epi Stathopoulos, and union problems of the 1950s, Gibson was able to take advantage of the uncertainty, paying just $20,000 for the company in 1957. They continued producing a handful of original Epiphone models in the USA, and created a range of new models (based on Gibson equivalents) until 1969, when production was outsourced to Japan.