Merriam-Webster on 'alright' Here
All right, everyone: listen up.
If you were listening when your English teacher said that, you probably learned that all right is the only way to write the word that is also sometimes spelled alright. Pete Townshend preferred the tighter version when he wrote the lyrics to The Who's famous song, The Kids are Alright, and James Joyce thought alright was better (in one instance out of 38) for Ulysses too.

Interesting that when they are trying to be correct they describe 'all right' as a word, rather than a phrase. Probably another example of variant American usage.