Solomon's Forced Labor Camps

1 Kings 5:13 King Solomon conscripted laborers from all Israel - thirty thousand men.

1 Kings 9:21-22 Solomon conscripted the descendants of all these peoples remaining in the land - whom the Israelites could not exterminate - to serve as slave labor, as it is to this day. But Solomon did not make slaves of any of the Israelites; they were his fighting men, his government officials, his officers, his captains, and the commanders of his chariots and charioteers.

There is no contradiction in these verses as there are different Hebrew words being employed and thus two different types of laborers are being discussed. 1 Kings 5 is referring to Israelite and non-Israelite labor force ((mas or hammas) within all Israel. In addition, 1 Kings 9:22 should be translated within the context of verse 21, which says, "Solomon conscripted the descendants of all these peoples remaining in the land - whom the Israelites could not exterminate - to serve as slave labor, as it is to this day." The Hebrew word used here (mas-obed) means forced-labor, but is not referring to Israelites. 1 Kings 9:22 states that Solomon did not employ any Israelites as slaves (abed).

There are some other/related opinions. P.R. House states:

Scholars disagree about the identity of the thirty thousand Israelite laborers mentioned in 1 Kings 5:13. Part of the problem stems from 1 Kings 9:20-22, which describes Solomons forced labor, then states, But Solomon did not make slaves of any of the Israelites (9:22). Gray, Skinner, Matheney, and others think these two references (1 Kings 5:13-18 and 1 Kings 9:20-22) contradict each other; Keil, Patterson and Austel, and Jones disagree. Linguistic analysis may help explain the perceived contradiction, since the text uses different terminology to describe the laborers in 1 Kings 5:13-18 and 1 Kings 9:20-22. In the former text they are called simply laborers (mas) while in the latter they are called servant [slave] laborers (mas 'obēd). Apparently, the Israelite workers were required only to toil four months of the year until the task was done. Forced labor does not necessarily entail slavery. On the other hand, foreign workers were permanently assigned to forced labor.

Another difficulty arises when one compares 1 Kings 5:15-16; 9:23; 2 Chronicles 2:17-18; 8:10. The first passage mentions 150,000 laborers beyond the 30,000 listed in 1 Kings 5:13 and also states that 3,300 foremen supervised the project and directed the workmen. On the other hand, 1 Kings 9:23 says 550 officials led the work project. Further, 2 Chronicles 2:17-18 states that the 150,000 were non-Israelites and that 3,600 foremen were assigned to keep the people working. Finally, 2 Chronicles 8:10 claims 250 officials supervised the forced labor. Interestingly enough, Kings and Chronicles each arrives at 150,000 foreign workers and 3850 foremen, but by counting them differently. The exact numbers make an outright contradiction unlikely. Why the variance? Keil probably answers this question when he writes:

We must therefore follow J. H. Michaelis, and explain the differences as resulting from a different method of classification, namely, from the fact that in the Chronicles the Canaanitish overseers are distinguished from the Israelitish (viz. 3600 Canaanites and 250 Israelites), whereas in the books of Kings the inferiores et superiores prefecti are distinguished. Consequently Solomon had 3300 inferior overseers and 550 superior (or superintendents), of whom 250 were selected from the Israelites and 300 from the Canaanites (Keil, I and II Kings).

Reference

P.R. House. The New American Commentary, Vol.8, 1, 2 Kings Nashville: Broadman & Holman Publishers), 1995.