Change comes very slowly and then all at once. For 80 years, architectural modernism has held sway in the West. And now, suddenly, the spell is breaking, most notably in the US. This week, President Donald Trump decreed that classical or traditional styles should be preferred for federal buildings as part of his executive order “Make Federal Architecture Beautiful Again”.

Five years ago, in the dying days of his first presidency, he tried the same thing, signing an EO to reorient federal architecture to traditional styles. Architectural panjandrums cried: “fascism!” Only dictatorial regimes, they asserted, have state-decreed architectural preferences. Factually, this was nonsense. The previous regime, the Design Excellence Programme, favoured modernist buildings. It only permitted the merest handful to be traditional (only 6 out of 78 of those commissioned). Trump was changing the direction and transparency of the preference but not the principle. Joe Biden then swept away his predecessor’s decree.

But this time, the President may just succeed. He is also eyeing a return to tradition at Penn Station in New York City. The original 1910 Pennsylvania Station by McKim, Mead and White was a sublime Beaux-Arts masterpiece which somehow echoed Rome’s Caracalla Baths into the design of a modern public transport hub. Its 1963 demolition in favour of one of the world’s ugliest stations, a subterranean shopping centre with tracks, was, according to The New York Times, a “monumental act of vandalism”. Once “one entered the city like a god, one scuttles in now like a rat” lamented art historian Vincent Scully. Funded by a Republican donor, detailed classical reconstruction plans now exist and Trump has apparently been in touch with the plan’s backers. What seemed fanciful is now imaginable.

The biggest change, however, is the wider mood. Trump’s executive order was provocative five years ago. The new order has, so far, landed more quietly. The Overton Window is moving. Many New Yorkers, certainly the ones I know, who want a classical Penn Station are Democrats. Trump’s advisers are also being cannier than last time: they are hard-wiring changes into the General Services Administration which implements the order and placing allies on the National Capital Planning Commission.

Agreement on this is not surprising. Biden’s return to modernism was very popular with architects. However, the results were not popular with the American public. In a carefully controlled Visual Preference Survey, around three-quarters of all races, creeds and political persuasions preferred traditional design for federal buildings. Architecture, it seems, can unify a people divided.

Globally, a revolt against traffic-modernism is underway. Step by step, country by country, from Left and from Right, from rich and from poor, the cult of architectural modernism is dying.

In Africa, traditional homes are being built again. In India, traditional villages and ecosystems are being created for the first time in 100 years. Across Europe, student demand is spawning traditional-architecture summer schools to teach what architecture schools will not. Growing understanding of neuroscience is teaching us that design is not subjective and most people agree on what we find ugly and it makes most of us sad. Even on BBC Radio 4, boundary-pushing designer Thomas Heatherwick has criticised modernism’s inhumane “cult”.

The spell has broken. The state should not dictate styles nor how we live. However, when it spends our money, it should heed public preferences. There are Right-wing and Left-wing versions of this counter-reformation, not to mention apolitical ones. Trump is just one part of this. So is King Charles III. And the monarch is winning too. His new “old” town of Poundbury, once architecturally vilified, is now widely agreed to be a runaway success. Architecture may be the one thing that Trump and Charles can agree on at their forthcoming state banquet.