The History of Sales Letters: How a Simple Format Built Billion-Dollar Industries

Why the Sales Letter Matters More Than Any Other Format

Every format in direct-response marketing — every sales page, every VSL, every email sequence, every product launch funnel — descends from a single ancestor: the sales letter. Not the banner ad. Not the TV spot. Not the social media post. The sales letter.

This is not nostalgia. I have spent over 30 years writing in the direct-response tradition, generating $523M+ in tracked results across health, finance, technology, and e-commerce. I have written for Apple, IBM, and Microsoft. I have written for ClickBank vendors and DTC brands. The formats change constantly — what the market wants today is different from what it wanted five years ago. But the underlying structure of the sales letter has never changed. Not once.

What follows is the history of how that structure was discovered, refined, and transmitted across generations — and why understanding that history makes you a better copywriter, marketer, or business owner today.

The Mail-Order Origins: 1870s–1920s

The sales letter did not begin with a copywriter. It began with a merchant who could not meet his customers face to face.

Aaron Montgomery Ward launched the first general merchandise mail-order catalogue in 1872 — a single printed sheet listing products with descriptions, prices, and ordering instructions. It was primitive by modern standards. But it established the fundamental premise that would drive the next 150 years of direct response: written words, delivered through the mail, could persuade someone to send money for a product they had never seen or touched.

Sears, Roebuck and Co. followed in 1888 with a catalogue that grew from a watch-listing flyer into a 500-page book known as the "Consumer's Bible." The Sears catalogue is one of the most important documents in marketing history — not because of its scale, but because of what its writers discovered through sheer repetition. Product descriptions evolved from bland specifications into persuasive arguments. Benefit language replaced feature language. Guarantees appeared. Urgency language crept in. The writers were not following a formula — they were discovering one, driven by the simple pressure of needing to sell more units than the previous edition.

By the early 1900s, the core elements of the sales letter were visible in the best catalogue copy: a compelling opening that grabbed attention, specific benefits that created desire, proof elements that built credibility, and clear instructions for ordering. The structure was emerging organically because it matched how people actually decide to buy.

Claude Hopkins and the birth of scientific selling

Claude Hopkins transformed sales writing from an intuitive craft into a testable discipline. His 1923 book Scientific Advertising argued that advertising should be treated like a science — with hypotheses, controlled tests, and measurable outcomes. He pioneered coupon-based response tracking, split testing, and what he called "reason-why" advertising: giving the reader logical, specific reasons to buy rather than vague claims.

Hopkins wrote some of the earliest recognisable sales letters — long-form persuasive arguments delivered through the mail, designed to generate a direct, trackable response. His insistence on measurement meant that every element could be tested and improved. This discipline — test everything, assume nothing, let the results decide — became the philosophical foundation of the entire direct-response industry.

“The time has come when advertising has in some hands reached the status of a science. It is based on fixed principles and is reasonably exact.”

Robert Collier and the Personal Letter: 1930s–1950s

If Hopkins gave the sales letter its scientific rigour, Robert Collier gave it its voice.

Collier's The Robert Collier Letter Book, first published in 1931, remains the definitive text on writing persuasive letters. Where Hopkins focused on measurement and testing, Collier focused on psychology — specifically, the idea that a sales letter must "enter the conversation already taking place in the customer's mind."

This single principle changed how the best copywriters approached the format. Instead of starting with the product and its features, Collier taught writers to start with the reader — their existing desires, fears, frustrations, and beliefs. The letter had to meet the reader where they already were, then guide them toward the desired action.

Collier also established that the sales letter should read like a personal letter from one human being to another. Not a corporate communication. Not an advertisement. A letter. This voice — intimate, direct, conversational — became the signature tone of the most successful direct mail copywriting for the next century.

The structure solidified during this period into the sequence we still use today:

• Headline — stop the reader and create enough interest to start reading
• Lead — hook the reader by connecting to their existing problem or desire
• Body — build the case through story, mechanism, and proof
• Proof — demonstrate that the claims are real through testimonials, data, and credentials
• Close — present the offer, remove risk, create urgency, and demand action

This architecture was not invented by any single person. It was discovered through decades of testing and refinement by hundreds of practitioners. But by the 1950s, it was established, and every copywriter worth their fee understood it.

The Golden Age of Direct Mail: 1960s–1990s

The period from roughly 1960 to 2000 was the golden age of the sales letter. During these four decades, the format reached its highest level of sophistication, generated its largest revenues, and produced the practitioners whose work still defines the craft.

Eugene Schwartz and the strategic framework

Eugene Schwartz's 1966 book Breakthrough Advertising gave the sales letter something it had never had before: a complete theoretical framework.

Schwartz introduced two concepts that remain the most important strategic tools in copywriting. The first was the five levels of customer awareness — Unaware, Problem-Aware, Solution-Aware, Product-Aware, and Most Aware — which told the copywriter where to enter the conversation based on what the prospect already knew. The second was market sophistication — a model describing how markets evolve from naive to skeptical, and how the sales letter must adapt its approach as sophistication increases.

Before Schwartz, great sales letter copywriters operated on instinct refined by experience. After Schwartz, they had a map. His framework meant you could analyse a market before writing a word and know — strategically, not intuitively — what your headline needed to do, how your lead should open, and what kind of proof the audience would require.

I cannot overstate how much this matters. Every sophisticated sales page I have written in 30 years operates within the framework Schwartz defined. When I work with a ClickBank vendor launching into a saturated health market, I am applying Schwartz's sophistication model. When I write a VSL for cold traffic, I am thinking about awareness levels. His work is not historical — it is operational.

Gary Halbert and the revenue machine

Gary Halbert was the practitioner who proved what the sales letter could do at scale. Operating from the 1970s through the early 2000s, Halbert wrote direct mail pieces that generated hundreds of millions of dollars in revenue. His "coat of arms" letter — mailed to millions of households — is one of the single most profitable sales letters ever written.

Halbert's genius was not theoretical. It was tactical and strategic simultaneously. He understood that a great sales letter started with a great market (his "starving crowd" principle). He understood that the envelope had to earn the open before the letter could earn the read. He understood that writing to one person at a kitchen table produced copy that outperformed writing to a demographic segment.

His newsletter, The Gary Halbert Letter, became the training ground for a generation of copywriters. His Boron Letters — written to his son from prison — remain one of the most accessible introductions to direct-response copywriting principles ever produced. And his actual mail pieces are still studied, swipe-filed, and reverse-engineered by serious practitioners.

The testing infrastructure

What made the golden age golden was not just the talent — it was the infrastructure. By the 1970s, the direct mail industry had developed sophisticated testing methodologies. You could mail 5,000 pieces with Headline A and 5,000 with Headline B, measure the response rate of each to two decimal places, and know with statistical confidence which version was stronger.

This testing discipline produced extraordinary precision. Copywriters discovered that:

• Changing a single word in a headline could double or halve response
• Long letters (8–16 pages) consistently outsold short letters (1–2 pages) for complex offers
• The P.S. was the second most-read element after the headline
• A strong guarantee increased sales more than it increased refunds
• The Johnson Box — a bordered summary at the top of the letter — could lift response by 10–25%

These were not opinions. They were tested, measured, verified findings. And they formed the evidence base that copywriting formulas and best practices still rely on today.

“The principles I use today to write sales pages generating six and seven figures in revenue are the same principles that were proven through direct mail testing in the 1970s and 1980s. The medium changed. The architecture did not.”

The Digital Migration: 1990s–2000s

The internet did not kill the sales letter. It liberated it.

When direct marketers first moved online in the mid-1990s, they did what any sensible practitioner would do: they took what worked and transplanted it into the new medium. The first online sales pages were literally direct mail sales letters converted into web pages — long, scrolling, text-heavy pages with the same headline-lead-body-proof-close architecture that had been generating revenue through the mail for decades.

And they worked. Immediately.

This should not have been surprising, but it surprised many people in the emerging "internet marketing" world who assumed that the web required entirely new approaches. It did not. The persuasion psychology was medium-independent. A compelling headline stopped a web reader just as effectively as it stopped a mail reader. Problem agitation built urgency on a screen just as it did on paper. Proof and testimonials earned trust in pixels just as they did in print.

What the internet changed

The internet did not change the structure of the sales letter. But it changed the economics, and the economics changed everything else.

No printing or postage costs. In direct mail, every additional page cost money. A 16-page letter cost more to mail than an 8-page letter. This economic constraint created a natural pressure toward concision. Online, length was essentially free. This meant sales letters could be as long as the persuasion required without any incremental cost — which is why long-form sales copy became the dominant format for high-converting online offers.

Instant testing. Split testing a headline in direct mail took weeks and thousands of dollars. Online, you could test a headline in hours for a fraction of the cost. This accelerated the optimisation cycle dramatically and made conversion rate optimisation a continuous discipline rather than an occasional event.

Multimedia integration. The physical sales letter was text on paper. The digital sales page could include images, video, audio, interactive elements, and dynamic content. This opened new possibilities for proof (video testimonials), demonstration (product walkthroughs), and engagement (embedded order forms) that the physical format could not support.

Global reach at zero marginal cost. A direct mail campaign to 100,000 people required 100,000 letters to be printed, stuffed, stamped, and posted. A digital sales page reached anyone with an internet connection at no additional cost per visitor. This changed the unit economics of direct response fundamentally.

The Modern Sales Letter: 2010s–Present

The sales letter did not stop evolving when it moved online. Over the past 15 years, it has spawned multiple descendant formats — each adapted to a specific channel and consumption pattern, but all built on the same persuasion architecture.

The long-form sales page

The most direct descendant of the traditional sales letter. A long-form sales page follows the identical structure — headline, lead, body, proof, offer, close — but leverages digital formatting for scanability. Subheadings break the text into digestible sections. Bullet points deliver benefits in compressed form. Testimonial blocks, comparison tables, and value stacks use visual hierarchy to reinforce the persuasion argument.

The best sales page examples in any market today would be instantly recognisable to a 1980s direct mail copywriter. The design is different. The architecture is the same.

The VSL (Video Sales Letter)

The VSL emerged in the late 2000s when bandwidth made online video consumption practical. A VSL is a sales letter delivered through video — the script follows the same headline-lead-body-proof-close architecture, but adds vocal tone, pacing control, and the intimacy of a human voice speaking directly to the viewer.

VSLs became the dominant format on platforms like ClickBank and in the DTC supplement space because they combined the persuasion power of a long-form letter with the engagement qualities of video. I have written VSL scripts that outperformed text sales pages by 200–300% — not because the words were different, but because the medium added emotional dimensions that text alone could not deliver.

The email sequence

Email copywriting is the closest modern equivalent to the follow-up letter campaigns that direct mail copywriters used to increase response. A well-structured email launch sequence is essentially a sales letter broken into chapters — each email advancing the persuasion argument, building anticipation, and driving toward the close.

The parallel is almost exact. The subject line serves the same function as the direct mail envelope — it earns the open. The opening line serves the same function as the letter's lead — it earns the read. The body advances the argument. The close drives action. If Robert Collier were writing today, he would be writing email sequences.

AI-personalised sales messages

The newest evolution is AI-driven personalisation, where the sales letter architecture adapts in real-time based on the individual reader's behaviour, preferences, and stage in the buying journey. The headline changes based on the traffic source. The lead adjusts based on the reader's awareness level. The proof section emphasises different testimonials based on the reader's industry or demographic.

This is not a departure from the traditional sales letter. It is the fulfilment of its original promise — a personal letter from one person to another — achieved at scale through technology that earlier generations of copywriters could only dream of.

The Structure That Never Changed

Here is the remarkable thing about this 150-year history: the fundamental structure of the sales letter has not changed. Not in substance. Across every era, every medium, every technological revolution, the architecture remains:

1. Headline — capture attention and create enough interest to earn the read
2. Lead — hook the reader by connecting to their existing problem, desire, or curiosity
3. Body — build the case through story, mechanism, credibility, and escalating desire
4. Proof — demonstrate that the claims are real with evidence the reader cannot dismiss
5. Close — present the offer, reverse the risk, create urgency, and demand action

Montgomery Ward used this structure in 1872 catalogue copy, even if he did not have a name for it. Hopkins codified its testing in the 1920s. Collier perfected its voice in the 1930s. Schwartz built its strategic framework in the 1960s. Halbert maximised its revenue potential in the 1980s. Digital marketers transplanted it online in the 2000s. And in 2026, it powers every high-converting sales page, VSL, and email sequence on the internet.

The structure persists because it mirrors the human decision-making process. People do not buy impulsively on complex purchases. They follow a psychological sequence: awareness of a problem, interest in a solution, desire for a specific outcome, belief that this solution will deliver it, and finally action. The sales letter structure maps directly to this sequence. That is why it works in every era — not because of tradition, but because of psychology.

What This History Teaches Modern Copywriters

If you write sales copy in any format — pages, VSLs, emails, ads — understanding this history gives you practical advantages that surface-level training does not provide.

The structure is non-negotiable. Every generation of copywriters who tried to "reinvent" the sales letter by abandoning its core architecture produced work that underperformed. The structure exists because it works. Learn it, respect it, and adapt it to your medium — but do not replace it.

Proof is the element that separates eras. The biggest evolution in the sales letter has not been in headlines or leads — it has been in proof. Early catalogue copy relied on company reputation. Golden-age direct mail relied on testimonials and endorsements. Modern sales pages rely on layered proof stacks — data, testimonials, case studies, demonstrations, and credentials presented throughout the copy. As markets grow more sophisticated, the proof bar rises. Meeting that bar is what separates famous copywriters from forgotten ones.

Testing discipline is the throughline. From Hopkins' coupon tracking in the 1920s to modern multivariate testing, the copywriters who produced the best results were the ones who tested the most rigorously. This is not a nice-to-have — it is the defining practice of the direct-response tradition. If you are not testing, you are guessing. And guessing is expensive.

The medium is replaceable — the principles are not. Physical mail, web pages, video, email, AI-personalised messaging — the delivery mechanism changes every decade. The persuasion principles do not. Write for the medium your audience consumes. Build on the architecture that has been proven across every medium that came before.

Carrying the Tradition Forward

I started writing sales letters when direct mail was king. I have watched the format migrate to the web, adapt to video, integrate into multi-channel funnels, and begin its latest evolution into AI-personalised messaging. Through every transition, I have observed the same thing: the copywriters who understood the history and the underlying architecture adapted successfully. The ones who treated each new medium as a blank slate struggled to produce results.

The sales letter is not a relic. It is a living, evolving format — the most successful persuasion architecture ever developed. Whether you are writing a long-form sales page for a DTC supplement brand, a VSL script for a ClickBank launch, or an email sequence for a SaaS company, you are working within a tradition that stretches back over a century. Understanding that tradition does not limit you — it gives you a foundation that makes everything you write more effective.

If you want a copywriter who has spent 30+ years operating within this tradition — writing sales letters, sales pages, VSLs, and email campaigns that have generated $523M+ in tracked results — I would welcome the chance to discuss your project. Get in touch here and let us talk about what the sales letter format can do for your business.