If for most of recent urban history the preferred form of footwear for men in a city was the shoe, we have definitively entered a new era — the Age of the Sandal. This decidedly unscientific observation is based on a recent walking tour of Manhattan from top to bottom — Inwood to Battery Park — on the East and West Sides. Though things may be different in other American urban centers, this reporter tends to doubt it.

Everywhere, in every setting, above and below ground, people — male-identified people — were flaunting their toes. Whether they were doing this because, as Women’s Wear Daily reported in July, we are in the middle of a booming sandals trend, or merely because it is so hot, who can know?

There is no question that luxury labels have leaped on the bandwagon. During the spring runway shows in Europe, designers paired safari jackets, “Miami Vice” pastels and drapey Armaniesque ’80s suits with footwear that gave full ventilation to heel and toe. Well before Justin Bieber was spotted exiting Bar Pitti in Greenwich Village in June shod in a pair of Mary Janes, a look that purportedly set off an instantaneous trend (never mind that Mary Janes are practically combat boots relative to Havaianas), lifestyle magazines as diverse as GQ and Ebony were already aggressively hyping skimpy footwear.

Sandals are now produced by labels that are world renowned, obscure and available at every price point. There are Greek fishermen sandals by the Copenhagen lifestyle company Vinny’s. There are slides like the ones Véronique Nichanian paired with relaxed-fit trousers and cashmere cardigans at Hermès. There are clog-style slip-ons like those produced by Rick Owens, Bottega Veneta and the Row. The Manolo Blahnik crisscross Otawi sandals are, at $675 a pair, an exorbitant version of the ones your uncle wears to grill hot dogs. There are, inevitably, Birkenstocks.

Let us pause for a moment to consider again the astonishing transformation of what was, at one time in the not-so-distant past, a niche hippie staple, mostly popular among commune dwellers and people who shopped in the Brattleboro Food Co-Op. Now, it’s the Type O blood of footwear, a fashion universal. Judging from my walking tour of Harlem, Midtown Manhattan, Greenwich Village and SoHo over several sweltering summer days, the sandal of the season is, without any doubt, the Birkenstock Arizona (or, for the more fashion forward, the big-buckle Madrid). Both models were so ubiquitous on city streets that it left little doubt as to why the 250-year-old company reported revenues of nearly $1.6 billion last year.

And while Birkenstocks provide marginally more foot coverage than the flip-flops that the designer Tom Ford once famously told People magazine he “wouldn’t be caught dead wearing,” they still produce an egregious display of toes perhaps not previously deemed suitable for city streets.