Tim De Chant at Per Square Mile has noted that rich urban areas have way, way more trees than poor areas in the same city. In fact, the difference is so stark that income inequality can be seen from space. The satellite images above are low-income West Oakland and high-income Piedmont, and I probably don't have to tell you which is which.

Forty years ago, in 1970, little Lisa Brown was riding her totally rad banana-seat bike through the woods of Cape Cod. She approached the Herring River, but the only way to cross it was a rickety plank board bridge. When Brown started out on the bridge it was two feet wide, but halfway across it narrowed to 12 inches, and she had to turn just a little bit to stay on track.

In a split second, she was in the river.

"I went in with the bike, I floated to the surface, I kicked away from the bike, and I must have pushed it down way into the mud," she told Cape Cod Times.

Brown came out "smelling like a snapping turtle,” and her bike was nowhere to be found. Until one recent day, when her wife Deirdre spotted a glint of metal off a nearby path.

She's off to school, with helmet on head and doll in tow. (Photo by carfreedays.)

A small federal program is punching holes through the unsafe barricade of freeways, busy roads, and rushed drivers that surround the nation’s schools. Yet despite the program’s success, Congress is now threatening to terminate it -- not to save money, but to redirect its funds toward more car-centric infrastructure.

In 2005, Congress initiated a Safe Routes to School (SRTS) national partnership. The SRTS program coordinates infrastructure improvements across the country to make walking and biking to school safer and more practical for students and educators. By most measures, the program has been a resounding success.

Testifying to Congress about a pilot project, director Deb Hubsmith stated, "In only two years, we documented a 64 percent increase in the number of children walking, a 114 percent increase in the number of students biking, a 91 percent increase in the number of students carpooling, and a 39 percent decrease in the number of children arriving by private car carrying only one student."

Children represent over 12 percent of pedestrian fatalities. And bicycle-related injuries send over a quarter million children to hospitals annually. But SRTS currently receives just 0.2 percent of the U.S. Department of Transportation's safety budget -- and even that tiny slice is now in jeopardy.

On Monday, 64 Kenowa Hill High School seniors biked to school in Walker, Mich. Nice, right? Well, the principal didn’t think so. She suspended the kids for the day and threatened to keep them from walking in their graduation ceremony. Somehow, this one story manages to encapsulate everything that is wrong with American attitudes towards biking.

The group ride was conceived as a less-destructive alternative to the traditional vandalize-the-school, get-everyone-out-of-class brand of senior pranks. Skipping lightly over the fact that a few dozen students riding bikes qualifies as a “prank” rather than a “Monday,” these kids actually deserve a lot of praise for organizing a group activity that’s healthy for them, the planet, and the community, instead of just pulling fire alarms.

And indeed, they got some praise -- the mayor even showed up to hand out donuts. But when the “bike parade” arrived at school, the principal had a major freakout and sent the kids back home.

And here is my face right now: 8O

Like other stuff that is good for your health (not smoking, sobriety, living slow, and dying old), bike helmets are uncool. But you can’t really enjoy your coolness with a giant crack in your skull. How do you protect your noggin without sacrificing your mojo? Swedish company Hovding has the answer: airbag bike helmets.

Unless it’s called upon to perform, this helmet stays safely stowed in a futuristic-looking black collar that you can pretend is a scarf. (Hovding also offers printed shells that go around the collar, to make it even more chic.) But if you get hit, presto, it bursts open like a popcorn kernel:

(Fast-forward to 00:36 for the slow-motion version.)

Almost all buildings have the potential to become energy-saving superstars. (Photo by Kevo89.)

In the 12 years since the debut of LEED certification, the green-building stamp of approval has become the holy grail for every earth-loving contractor and home-builder. But while brand-new, Dwell magazine-worthy eco-structures are a flashy way to highlight new construction practices, the greenest buildings, it turns out, are almost always old ones. By fixing up an old building, you’re saving the planet all the costs of growing, manufacturing, and shipping new building materials all over creation, putting yourself decades ahead of a new building in terms of mitigating climate impacts.

LEED has a special set of awards (silver, gold, platinum) for existing buildings that have energy efficiency retrofits and other upgrades, but these rising energy-saving superstars haven’t seen much limelight -- until now. Next month, the first annual EBie Awards will recognize impressive environmental performance improvements in existing buildings (existing buildings – E.B. – get it?).

“There’s not been enough recognition of the talent and skills that go into making effective change through existing buildings,” says Russell Unger, executive director of the Urban Green Council, which created the awards. “By bringing these incredible case studies to light, we’re hopefully encouraging duplication. People will start asking themselves, ‘Why can’t I do that, too?’”

A version of this article originally appeared on Transportation Nation.

Subway and bus ads are the latest battleground between New York Mayor Michael Bloomberg’s health department and soda makers. The newly formed New York City Beverage Association is taking a huge mass transit ad buy as part of a $1 million campaign to rebut the city’s claim that soda is unhealthy.

For months, the city has been running public service announcements linking sugary drinks to mountains of fat and waterfalls of sugar, including a graphic video (below) that claims drinking a can of soda a day can add 10 pounds in a year by showing a man pouring fat out of a can of soda and drinking it.

This year marks the 10th anniversary of our Ask Umbra advice column, and to celebrate, we’re pulling one particularly poignant question or tidbit of eco-advice out of the archives each week. Today, May 18, is Bike to Work Day. After we hung up our helmets and checked out the news cycle, we took a trip down memory lane with this Umbra video classic on commuting by bike. 

What's that you say? You're already in your cubicle, miles from your trusty single-speed? We have two more weeks of National Bike Month. Even if you missed the chance to ride with all the cool kids today, there's still plenty of time to get your fixie fix.

Oh sure, you could hang around with lizards and cavemen and pink-haired spy chicks and that irritating "Fran" woman, trying to save a few bucks. Or you could cut to the chase.