The first predecessor, the AIEE (American Institute of Electrical Engineers) was first formed in May 1884 after the growth in use of electrical technology such as telegraph, electrical infrastructure and electrical devices. The aim was to promote the discipline. In the beginning, the AIEE focused mostly on wire communications and lighting and power systems, having to contend with internal factors such as locating sites for the headquarters, membership issues and trying to gain interest in emerging specialities.
The second predecessor the IRE (Institute of Radio Engineers) had similar goals and interests, so much so that by 1930, with the introduction of electronics, it was very hard to distinguish between the 2. After WWII, they became increasingly competitive with problems such as overlap and duplication of effort increasing. These were not decreased by the joint committees that they held.
In 1961, the leadership of both parties decided that it would be best if they combined their efforts and so the IEEE was born in 1963.