Raymond Loewy wrapped a 140-ton locomotive in one continuous curve, and a crowd fell in love with speed standing perfectly still. That teardrop logic now decides the corner radius of every button you tap.
Pennsylvania Railroad S-1 · styled by Raymond Loewy · shown at the 1939 fair, running in place on rollers
Curvature is not decoration. It is drag reduction — for the air in 1937, for the eye and the thumb ever since. Remove the sharp transitions and the whole form reads as one motion.
Streamlining began in the wind tunnel: continuous surfaces cut aerodynamic resistance. Then something strange happened — manufacturers put teardrop shells on refrigerators, pencil sharpeners, radios. Objects that would never move an inch borrowed the geometry of flight, because the public read the curve itself as progress. An engineering constraint had become an emotional signal. It never stopped being one.
Picture the Pennsylvania Railroad’s S-1 on its platform at the World’s Fair: a hundred and forty tons of steam engine sheathed in one welded, wind-smoothed shell, running at speed on rollers, going nowhere, drawing the largest crowds at the fair. Run your imagined hand along it — no rivets catching your palm, no seams, just cold rolled steel curving from nose to cab like water over a stone. Loewy had put clay models in an actual wind tunnel; the shape was earned. But its real job was theatrical: it made the future look inevitable.
Loewy understood the psychology he was exploiting, and he gave it a name: MAYA — Most Advanced Yet Acceptable. Humans are torn between neophilia and neophobia, love of the new and fear of the too-new. “The adult public’s taste is not necessarily ready to accept the logical solution to their requirements,” he wrote, “if the solution implies too vast a departure from what they have been conditioned into accepting as the norm.” So he advanced taste one notch at a time — the Coca-Cola bottle refined, not replaced; a locomotive that was radically new but unmistakably a locomotive.
Science later caught up with his instinct. Neuroimaging studies found sharp contours light up the amygdala — the brain’s threat detector — while curved forms are simply liked more, across cultures, in infants, even in great apes. The teardrop was never just aerodynamics. It was biology.
One button, four corner treatments. Tap through them and watch a rectangle become a capsule — and notice what your gut says at each stop.
inner radius = outer radius · wrong
Same 24px radius on the card and the button inside it. The gaps between the curves go lopsided — the shapes fight instead of nesting.
inner = outer − padding · right
24px outer, 16px padding, 8px inner. The curves stay concentric — one continuous surface, the way Loewy’s panels flowed into each other.
Apple hit the S-1 problem at icon scale: a rounded rectangle’s corner — where flat edge meets circular arc — has a tiny discontinuity the eye registers as noise, multiplied across a whole home screen. The fix was the squircle: corner curvature that builds gradually, so the shape reads like a pebble smoothed by a river, not a square that had surgery. The exact recipe — a radius near 22% of width with roughly 60% corner smoothing — is continuous-surface engineering, straight from the wind tunnel to the app grid.
Google systematized the same instinct as a token scale — Material’s shape system runs from square to full pill, and its newest version morphs shapes to signal state: a button rounding into a circle when selected is a teardrop nose telling you the machine is fast, before it moves. And the purest streamline survivor is the pill button itself: no vertices, no dead corners in the tap target, a shape that implies it is already going somewhere.
| Loewy, 1930s | Interface, 2026 | Shared physics |
|---|---|---|
| Teardrop nose on the S-1 | Pill button, capsule toggle | No hard stops — the form implies motion |
| One welded shell, no rivets | Squircle’s continuous curvature | Surface continuity quiets the eye |
| Horizontal speed lines | Progress bars, horizontal card decks | Implied velocity at rest |
| Chrome catching the light | One gradient sheen on the primary CTA | Highlight marks the hero, sparingly |
| MAYA — advance one notch | Incremental redesigns, phased rollouts | Novelty anchored to the familiar |
Most advanced. Yet acceptable.Raymond Loewy · the MAYA principle
Every rounded corner in your product is quoting a locomotive that ran in place at a fair. Nothing digital has drag; the curve is pure inherited emotion — which is exactly why it works, and exactly why you should spend it deliberately. Round the things you want trusted and tapped. Keep an edge where you want caution. Softness is a budget, not a default.
— Curator, Streamline Moderne