In writing historical fiction, one is faced with the dilemma of knowing how people really spoke. Often readers think of "ole timey" language as sounding British, even as recently as the early 1900s. Reading newspapers and other print at the time proves this is not the case. Here is an interesting response to the question of did people use contractions long ago on the StackExchange's Forum English Language and Usage and from Today I Found Out. Note: these are not primary resources, but show evidence of the use of contractions.
In all languages I know, there is a general tendency to contract existing words in speech. I will comment on contraction in writing later.
The cause of contraction in speech is probably that speakers pronounce words in an inarticulate manner when they say them fast, just as some say wanna when they pronounce want to. In general, the commoner a word is, the sooner it will be contracted or otherwise shortened. But contraction can happen at all times.
This also applies to the development of Latin into French, and the subsequent borrowing by English: Vulgar Latin bellus (beautiful), pronounced somewhat like /bel-loos/, became in French beau, pronounced somewhat like /bow/, as in the shooting instrument. So our word beauty (/byoo-ty/) comes from Vulgar or Late Latin *bellitatem (/bel-li-tah-tem/). This is an endless cycle: the contraction of *bellitatem probably happened in several steps, in which the resulting word from the previous phase was contracted into an even shorter form in a new contraction. And the Latin words were in many cases contractions of pre-Latin words.
In modern English, the more recent contractions, like I've, are marked as such in writing by apostrophes. This, and the fact that the full forms of those recent contractions, like I have, are still in use, makes it so that you still view I've as a contraction. But do you still consider beauty a contraction? What definition of contraction should we use? It is my estimate that the creation of new contractions in speech is a universal phenomenon that has always been practiced at a reasonably level pace, though there might be exceptions. That is why it is highly likely that we use more contraction than our ancestors: we contract the same words on average more often than they did, and we contract some words that they did not.
Contraction in writing
In writing, it all depends on how closely the pen follows the tongue. Consider I used to like her. The phrase used to is mostly pronounced /yoo-sta/: why don't we write it as us'to or yoosta? The contraction happens in speech, but it is not represented in writing. Our choice not to do so is often arbitrary.
As concerns the contractions that we write with apostrophes today, it is likely that they, too, were more often fully pronounced in 1800 than now. On the other hand, there are some written contractions that we do not use any more, such as 'tis and 'twere. That is because there are many other processes going on in the development of language all the time: words may get dropped from use all together, words may be changed in ways that do not make them shorter or longer, and speakers may consciously resist the use of contractions and try to reverse time by pronouncing them whenever they can; the ever-active tendency to contract is apparent on the larger scale, but not always on a smaller scale.
Historical statistics on contractions in writing
Now to the data. In English books, at least, the usage of our apostrophied contractions instead of full forms appears to have increased significantly. Compare the two following graphs from the Ngrams Viewer, which displays data from digitised books in Google Books. The graphs chart the total usage of "have" and "ve" as percentages of total usage of all words:
The same applies to "am" versus "m":
Notice that this development is much less distinct with "are" and "re":
These statistics are for all of English literature, but American usage gives similar graphs. Contractions have been used a lot since long before the 1800s; we just see here that they were used even more as time progressed. Note that it is uncertain to what extent usage in literature reflects speech. It is not impossible that some of the change you see here is due to changing practices among printers: perhaps before 1900 they used to write contracted verbs in full, even when they contracted them in their mind's ear, and this typographical convention changed later—I have no idea. It could also be that those who digitised these books used different transcription conventions for different blocks of years, e.g. the older books might have come from academic libraries and might have been digitised according to the guidelines of scholarly specialists.
You may have observed a few interesting facts:
After an initial rise, the temporary decrease in the usage of contractions in 1945–1965 is rather striking. Perhaps the social climate was more reactionary in those years. But this is mere speculation.
"Have" has always been used much more frequently than "ve", and "are" more than "re"; but "am" and "m" started much closer, and "m" even overtook "am" around 1975. You can see them all combined in this graph, which is, alas, a bit too small to compare the contracted forms very well:
Won’t, don’t, wouldn’t, isn’t and even ain’t- where would we be without our contractions? Prevalent in spoken English and increasingly accepted in written pieces, contractions enable brevity and make written works more accessible and friendly.
Contractions in some form of English date back to Old English (450 AD – 1150 AD), a language that bears little resemblance to our English today. Before this period, although the Romans had already invaded, the dominant language on the island was Celtic. In the 5th century, several groups, notably the Angles and the Saxons, began to invade, and they brought their Germanic languages and rune alphabets with them, along with several well-established contractions. These included shortened forms for “is not” (nis, today, “isn’t”), “did not have” (ne haefde), “was not” (ne waes, today “wasn’t”) and “would not” (wolde, today “wouldn’t).
During the Old English period, Christian missionaries introduced Latin as well as the Roman alphabet, so by the time the Normans appeared in the mid-11th century, the language was ready to incorporate a fair bit of French, the language of post-Conquest English nobility. (In fact, King Richard “The Lionheart” barely spoke English, and only spent about six months in the country he was king of for the decade he was king.)
Nonetheless, the common people continued to speak English, although now peppered with thousands of French words and conventions, and eventually, this pidgin developed into Middle English (1150 AD to 1450 AD). Far easier for a modern English speaker to understand, it was during this period that negative contractions (i.e. using “not”) arrived on the scene in the form of ne were (“were not”) and noot (“knows not”). Other contractions from this period include thilke (for “the ilke” meaning “the same”) and sit (a shortened form of sitteth).
By the turn of the 16th century, the Renaissance arrived in England and with it came further changes to the language, which by this time is recognizable as Early Modern English (1450 AD to 1750 AD). Latin and Greek words were adopted and altered (e.g., militia, squalor, illicit and explain), and men like Shakespeare were introducing new words to the masses at a rapid pace (e.g., assassination, cold-blooded, eyeball and fashionable).
Some contractions that appear during the Early Middle English period include I’ll (I will), ‘twould (it would) and ’twill (it will), as well as negative contractions of every form including can’t (cannot), don’t (do not), shan’t (shall not), mayn’t (may not)and won’t (will not). According to the Online Etymology Dictionary, won’t first appeared at the dawn of the period in the mid-15th century as wynnot and then wonnot, and its modern form in the mid-17th century. Don’t was first recorded in the 1630s, and can’t first appeared in print in 1706. Ain’t also first appeared in 1706 as a contraction only for “am not,” although by the early 1800s, it was also used to mean a variety of negatives including “are not,” “is not,” “have not,” and “has not.”
As you might have guessed from all this, contrary to what the latest True Grit film would seem to indicate, contractions were around long before Mattie and Rooster were attempting to avenge her father. However, during the period in which the character of Mattie was off on her adventure (1880s), in formal writing contractions were absolutely disfavored. This is a trend that started in earnest around the late 18th century. However, as we can see by the works of Mark Twain (1835-1910), among many others who wrote certain characters speaking the way real people actually talked in this era, in everyday speech, contractions seemed to have been the norm.
So why did the Cohen brothers choose not to use them in their adaptation of the True Grit serials? Ethan Cohen explained in an interview, “We’ve been told that the language and all that formality is faithful to how people talked in the period.” While this is mostly true in formal writing, it was most definitely not in common speech, particularly for characters like Rooster Cogburn and Tom Chaney. And, in truth, the original True Grit serials, written in 1968 from the perspective of a woman writing in the 1920s, used “won’t” instead of “will not” about 36% of the time and “don’t” instead of “do not” about 60% of the time, among other uses of contractions.
As for today, despite the many years contractions have been taboo in formal writing, as with many grammatical sacred cows, time (starting around the 1920s) and more recently the Internet seems to have changed at least some people’s views of their acceptability in writing.
Nonetheless, apparently the APA still disapproves of them, according to many commentators, and the United Kingdom’s The Guardian newspaper cautions against overusing many contractions including can’t, aren’t, don’t, I’m and it’s even though “they might make a piece . . . easier to read, they can be an irritant and a distraction, and make a serious article sound frivolous.”
On the other hand, reference guides for AP style note that contractions found in reputable dictionaries are acceptable in informal writing, but should not be used excessively, and the Chicago Manual of Style goes further to say that “most types of writing benefit from the use of contractions,” although they should be used “thoughtfully.”
Experts in business writing generally approve of the use of contractions for creating a flowing style that engages the reader, but warn that when writing for an international audience where there will be non-native English speakers, contractions can be confusing and should be avoided.
Uncle Sam has even weighed in on the debate. Beginning in 1998 when President Bill Clinton issued an executive memo instructing federal agencies to write more plainly, the federal government has been trying to turn government jargon into readable English. Along with the 2010 Plain Writing Act signed into law by President Obama, these two directives have resulted in PlainLanguage.gov, a set of instructions for government employees to help them write documents Americans will understand.
Under these guidelines, writers are instructed to “use contractions when appropriate,” even with legal writing as they will render it “less stuffy and more natural.” To sum it up, the directive is “write as you talk,” but use discretion when including contractions.
Bonus Fact:
According to the University of Illinois’ Professor of English and Linguistics, Dennis Baron, we can also stop worrying about ending a sentence with a preposition. Never intended as a rule, it began when an 18th century wordsmith cautioned against placing a preposition at the end of a sentence when this will separate it from its verb by many words, as this makes the sentence awkward to read.