Carol Hummel's Tree Cosy, which won the Sculpture in the Heights Public Art Competition in Ohio in 2005. Photo / carolhummel.com
Maybe there are just not enough babies being born in America.
Whatever the reason, knitting nuts across the land have taken their skills outdoors, creating crocheted coverings for everything from whole trees to door knobs and park benches.
It is almost as if Cristo suddenly went stitch-crazy. But the artist famous for wrapping buildings and bridges is not the culprit here.
This is a more homespun phenomenon, with knitting fans of all skills latching on to the idea of adorning ordinary elements of the landscape with colourful jackets of wool, nylon and other synthetics.
Particularly popular is the tree cosy.
Residents of Columbus, Indiana, have covered 33 ornamental pear trees lining the town's main street with playful cosies.
They added arms to one of them and called it the "People Hugger".
One tree in Yellow Springs, Ohio, has had the crochet treatment - a cosy with little pockets - but it has become the talk of the region.
"What takes this to a different level is it is a community thing," said Corrine Bayraktaroglu, an artist who helped start the town's "knitknot tree" project.
"People are enjoying it. They're coming to have their photograph taken with the tree; they're adding stuff to the pockets."
Scholarship on this movement is woolly. But it may be traceable to the northern Ohio artist Carol Hummel, who attached a cosy to a tall tree at City Hall in Cleveland Heights several years ago.
"When I started this, crochet and knitting were not popular," she said yesterday.
"But in the past few years there has been a resurgence in knitting, inspiring a lot of this work. I guess my pieces are not unique any more. I will have to find something else to do."
She may stop, but others have just got started.
Recently spotted in Houston, Texas: crochet-covered car aerials, telephone poles and beer bottles.
- INDEPENDENT
Telegraph: This is what the right daily amount of protein looks like, meal by meal.