There are still probably a majority of teachers of English who take pains to discourage their pupils from using the spelling ‘alright’. This is one of the legacies of the authoritarian as opposed to the analytical, scientific approach. It is well known that considerable numbers of words, and expressions and pronunciations, not usually in a way one can easily detect (as eg with the verb escalate or the pronunciation of dispute with forestress), move from obscurity to being very widely used within the space of a few years.
This was very probably the case of ‘all right’ in the senses of ‘perfectly satisfactor(il)y’, or as an expression of assent. There is no trace of this expression until towards the middle of the last century and it is clearly highly idiomatic. The unity of the idea is clear from the fact that the expression’s existence in these meanings could not be deduced by someone whose mother tongue was not English from a knowledge of its separate components. It was quite natural that for many people who came to write it — and it remained very much an informal colloquial rather than a written expression for a long time (it still is likely to be avoided in elevated or dignified styles) — that they should wish to express visually this unity by distinguishing it from the mere sequence of the two component words as in eg ‘She got the sums all right’. They would wish to write it either with a hyphen or as a single word: in the latter case the fact that the usual pattern is for words with double l, like all to shed one l in combinations would lead to alright on the analogy of already, altogether etc.
The evidence for the earliest occurrences of the spelling alright appeared in the OED1 Supplement of 1933 when Onions listed three quotations as examples, one of 1925 from Lord Curzon, the earliest being 1893, and noted it without condemnation or any comment as a "frequent spelling’. OED2 added 1926 H. W. Fowler Modern English Usage 16/1 There are no such forms as all-right, allright, or alright, though even the last, if seldom allowed by the compositors to appear in print, is often seen .. in MS. This was the characteristic pedantry of that dilettante rather excessively respected arbiter of usage.
No doubt many people who grew to maturity in the nineteenth century found the expression disagreeably newfangled and at least theoretically avoided using it, as for instance many of more recent generations have reacted to the exactly parallel ‘okay’. Such people and many others who had, whatever they felt about it, not seen it so written would be reluctant to write it as one word. If the spelling had been an extremely rare usage, however logically acceptable and harmonious with other customary spellings, it would still have been perfectly defensible to describe it as ‘wrong’ in the sense of having no currency, quite unsanctioned by usage.
However, there was no excuse for him in 1926 when H. W. Fowler published his now far from Modern English Usage. His unjustifiable comments were based on ignorance and prejudice: he said ‘should always be written separate’ adding that ‘there are no such forms as alright’ etc contradicting himself immediately by saying that they are ‘often seen’. Similarly self-indulgently in his Universal Dictionary of the English Language (1932) Henry Cecil Wyld permitted himself to describe alright as a ‘wrong form of all right’! It is, however, no doubt the uncritical awe in which Fowler has been held for generations that has resulted in slavish repetitions of such judgments. Ultimately, of course, the poor dog has thereby truly acquired something of a bad name. In the eighteenth tract of the happily long defunct Society for Pure English, published in 1924, Fowler was one of four contributors to an ‘open forum’ on the spelling. The others included C. T. Onions and Robert Bridges. Their comments were inconclusive. Arguments against it were either scientifically questionable or purely pragmatic.
The spelling has appeared in the Oxford Advanced Learner’s Dictionary labelled ‘non-standard or informal’. The Concise Oxford Dictionary labels it as a ‘disputed’ usage. It appeared in the Chambers Twentieth Century Dictionary (1972) labelled ‘unaccepted’ in the Hamlyn Encyclopaedic World Dictionary (1972) labelled ‘not generally regarded as good usage’. Of the popular American dictionaries the Standard College Dictionary (1966) said ‘not yet considered acceptable’, the American Heritage Dictionary (1969) said ‘a common mispelling’, the Random House Dictionary (1966) said ‘occasionally seen ... not considered acceptable in standard English’ but the truly authoritative Webster's Third New International (1961) contradicted them firmly by saying ‘in reputable use although all right is more common’. The 1972 Supplement to the Oxford English Dictionary saw fit to make no departure from C. T. Onions's 1933 acceptance of the spelling without qualificatory comment on its usage and acknowledged its frequency. So also OED2. The Longman Dictionary of Contemporary English (1978) happily included it, saying in a manner that rather typically put achievement of simplicity before avoidance of naivety, ‘Alright’ is very common now, but some people think ‘all right’ is better English’.
An advertisement for the newspaper Europa which appeared in The Times in the 1970s was headed boldly
The more orthodox spelling would surely have been much less felicitous in such a context.
In fairness to Fowler his judgments were not always so unsatisfactory. His recommendations about anyone, everyone, someone etc, which underwent a similar change from separate to solid over much the same period were alright. The solid spelling anyone didn’t get into the Concise Oxford Dictionary until 1951, though it was in the Pocket Oxford Dictionary in 1925. It would be a good to think that these days everyone allowed alright to be similarly used with no more of the complaints which were at one time at least such a waste of breath on the part of teachers who made them.