The rendering was king may be better translated by a verb like “reigned” (Revised English Bible) or “ruled” (New International Version, New Century Version) in certain languages.

Some translations of this verse say simply “Israel” (Revised English Bible) instead of all Israel. But the word all should be translated since the reference is to both the southern kingdom of Judah and the northern kingdom of Israel and because it is a part of the Hebrew text. Since it was immediately following the death of Solomon that the kingdoms of Judah and Israel separated, the author may be stressing the fact that at this point the separation had not taken place.

Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Kings, Volume 1. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here .