Obama, the Emancipation Proclamation, and copying from wikipedia

An article in the Washington Times titled Obama garbles U.S. history in human trafficking speech contains the text:

In making an impassioned plea for the international community to crack down on trafficking, Mr. Obama pointed out that his speech at the Clinton Global Initiative was taking place a few days after the 150th anniversary of President Lincoln issuing the Emancipation Proclamation in 1862.

“With the advance of Union forces, it brought a new day — that all persons held as slaves would thenceforth be forever free,” Mr. Obama said.

Actually, the Emancipation Proclamation freed slaves in 10 Southern states who were, at the time, mostly beyond the control of the federal government. And the document didn’t free an estimated 500,000 slaves in four slave-holding border states — Missouri, Kentucky, Maryland and Delaware — that were loyal to the Union. Slavery was ended in those states by various state and federal actions later on.

The article is correct that the impact on slavery was limited. Most importantly, the Emancipation Proclamation did not end slavery, so the idea that "all persons held as slaves" would be free, by virtue of the Emancipation Proclamation, is simply wrong.

In turn, however, the Washington Times article merely grabbed from wikipedia, which states:

The Proclamation applied only in ten states that were still in rebellion in 1863, thus it did not cover the nearly 500,000 slaves in the slave-holding border states (Missouri, Kentucky, Maryland or Delaware) which were Union states — those slaves were freed by separate state and federal actions.