Language is always changing, and most often in the direction of simplification.
You can even see the evolution happening before your own eyes.
"All ready" became "already" ; "all right" is in the process, through usage and repetition, of becoming "alright" (if not in fact "a'ight").
It is already accepted as an informal alternative to "all right" and I predict that it will supplant the two-word version altogether (!) except in the most formal writing (e.g., academic papers) within the lifetimes of many of us.
ell.stackexchange.com/users/68/Robusto
I would say that yes, there are contexts where only "all right" is acceptable.
As an example: Are any of the answers wrong?
No, they are all right i.e., all of them are correct.
I have found that alright seems to be following the example of all ready vs. already and all together vs. altogether.
In both cases, as I did above, one could add the phrase "of them are" to each of the former terms and make it completely clear what is meant, whereas each of the latter terms have entirely different meanings.
Alright has come to mean acceptable, okay, and safe, as in "the kids are alright" - very much a comforting phrase if there has been some kind of accident or the like! "
The kids are all right" in that same context would have an extremely confusing connotation: the kids would not all be correct after an accident.
I would also like to point out that the way a word or phrase achieves acceptance and legitimacy is by usage, and "alright" certainly has this on its side!
ell.stackexchange.com/users/2630/Warjna Waleska Kaztjmjr
It seems that historically, all right was the only accepted version.
Alright is more recent, and can either be seen as a shortened form of all right , or can have a slightly different meaning.
Something that is all right is in order, and we are at peace with it.
Something that is alright can be seen as simply satisfactory.
ell.stackexchange.com/users/25/Squazic
I checked four dictionaries and they all agreed that "alright" is an informal equivalent of "all right."
However, informal doesn't mean wrong; it merely means informal.
Thus, "alright" is perfectly acceptable in informal contexts.
ell.stackexchange.com/users/80/Scott Severance
Alright is technically incorrect, but common, and therefore, proper grammar.
It is used informally, as well as in situations where space isn't abundant, for instance, on signs and Twitter tweets.
It is also used in quotes within many stories due to its commonness of use.
ell.stackexchange.com/users/67/Mark Robinson
On top of answers of others — there are contexts where only "all right" is accepted, and I don't mean formal/informal.
— Are there any left-threaded bolts in the bin? — No, they are all right.
ell.stackexchange.com/users/30/SF.
Is there any difference between " alright " and " all right "?  I can find both forms in different articles (especially on the Internet), although  all right  seems to be more common.  I was wondering if both forms are acceptable or whether it is some sort of difference between American and British English or just a common mistake?
Difference between "alright" and "all right"?
ell.stackexchange.com
<word-choice><confusable>
ell.stackexchange.com/questions/147
ell.stackexchange.com/users/11/Tom
It seems that historically,  all right  was the only accepted version. Alright  is more recent, and can either be seen as a shortened form of  all right , or can have a slightly different meaning.   For example, something that is  all right  is in order, and we are at peace with it. Something that is  alright  can be seen as simply satisfactory or OK. Alright  is technically incorrect, but common, and therefore, proper grammar.  Four dictionaries all agree that "alright" is an informal equivalent of "all right." All right can mean everything is is in order, whilst alright is simply satisfactory/safe. Alright is a more recent development and can mean the same as all right. All right can also be meant in the sense of right/left.
All right can mean everything is is in order, whilst alright is simply satisfactory/safe. Alright is a more recent development and can mean the same as all right. All right can refer to right/left.