FWIW, the Oxford English Dictionary lists it as all right; note that it is a distinct entry from an earlier (now obsolete) word alright meaning "exactly, just".

FWIW, the Oxford English Dictionary lists it as all right; note that it is a distinct entry from an earlier (now obsolete) word alright meaning "exactly, just". Regarding the spelling, though, it notes: > The form alright is frequent, although more widespread in non-literary printed sources (e.g. newspapers and journals) than in literary texts. Compare the standard spellings of already (adj. and adv.), altogether (adj., n., and adv.), always (adv). Although these analogues exist, the form is strongly criticized in the vast majority of usage guides, but without cogent reasons. I suspect that while all right is generally regarded as the more "correct" form, alright will eventually be accepted as a valid alternative in modern usage, though traditionalists will be fighting a rearguard action for some years yet.