For decades, city-dwellers have fled to the clean, quiet and spacious American suburbs, where McMansions have popped up faster than you can say "Applebee's." But the suburbs are not proving to be recession-proof, as the latest Census data shows - while cities are growing nationwide, suburban growth is slowing. It's good green news, considering that the average city dweller has a carbon footprint that is much smaller than a suburbanite's. Says the Wall Street Journal:

The Census data underscored how the recession and the real-estate slump have curbed migration, especially to suburbs and outer areas known as exurbs.

The central-city population in U.S. metropolitan areas with more than one million people (excluding New Orleans, where recent growth rates reflect residents returning to the city following Hurricane Katrina) grew at an annual rate of 0.97% between July 2007 and July 2008, according to Mr. Frey's analysis. That compared with a growth rate of 0.90% in 2006-2007, and growth rates around 0.5% in the years between 2002 and 2005, when the robust real-estate market led to new jobs and new housing developments outside the cities, where open land is more plentiful.

At the height of our outdoor barbecue season—next weekend, more than 56 percent of Americans will make hot dogs and hamburgers for the Fourth of July—comes a film that may make those pleasures seem rather unpalatable. Robert Kenner's documentary "Food Inc." has been described as muckraking journalism, in the vein of Upton Sinclair's "The Jungle," for giving Americans a glimpse of what really goes on their plate—whether it's ammonia-washed hamburger filler, or chickens with genetically-modified breasts so large that the birds cannot walk.

It is especially relevant in an era in which diabetes rates continue to climb—and it's no wonder, when a fast-food cheeseburger is cheaper than fresh produce. In the past few months, we've seen peanut butter, pistachios, and now Nestle cookie dough recalled for containing pathogens. Kenner couldn't have timed the release of this film better if he had tried.

The long-awaited Cash for Clunkers legislation has passed, and is awaiting President Obama's signature. Here's what you need to know about the auto trade-in program.

1. What's the official definition of a clunker? A driveable car made within the last 25 years, with a fuel economy rating of no more than 18 mpg. To learn more about the combined city/highway fuel-economy of your car, check out the Car Allowance Rebate System site.

2. Here's how the program works: you trade in your old car for cash towards the purchase of a new, more efficient one. The better the mileage of the new car, the more money you'll get towards its purchase - either $3,500 or $4,500. Check out Jalponik's handy chart to figure out how much you might be able to claim.  The minimum combined fuel economy of a new car purchased under the program must be at least 22 mpg, while new small trucks and SUVs have to get at least 18 mpg, and large trucks have to get 15 mpg. The old cars will be salvaged once they're turned in.

3. Consumers should act fast. The bill provides vouchers for one million purchases, and the window of time is only fron July 1 to November 1. The bill will be revisited in the fall , and some changes may be made at that time.

Those monsters under the bed? Well, they're no scarier than dust bunnies now. According to Bjorn Lomborg, author of "The Skeptical Environmentalist," children are more frightened by a different sort of boogeyman - climate change. Lomborg writes in the Guardian that telling our children about climate change is "grotesquely harmful," citing pre-teens who cry about polar bears (maybe it's this kid?) and children who think the world is going to explode.

"Children believe that global warming will destroy the planet before they grow up because adults are telling them that ... The current debate about global warming is clearly harmful. I believe that it is time we demanded that the media stop scaring us and our kids silly. We deserve a more reasoned, more constructive, and less frightening dialogue."

Chipotle, the quick-service Mexican restaurant that dishes out hearty, foil-wrapped burritos is expanding its local foods program - last year, they sourced 25 percent of one bulk produce item used in each store from a local farm, and this year, they're expanding the program to 35 percent. For a chain with more than 860 restaurants, it's a large committment, but they've kept surprisingly mum about it. I talked to Chipotle's Chris Arnold, director of media relations, about the meaning and growing popularity of local food.

What was the catalyst for Chipotle to use local foods?
Better tasting food. We really believe that fresh ingredients from more sustainable sources are the way to go. Adding local produce to some of the things we had already been doing, including naturally-raised meats and dairy products made with milk from cows without RBGH, was the logical place to go. We're looking for sources for all of the ingredients that we use that share our commitment to raising animals and produce in ways that are better for the environment.

The terms "green," "natural" and "eco-friendly" sure don't mean what they used to. Today, the House Committee on Energy and Commerce held a hearing entitled “It’s Too Easy Being Green: Defining Fair Green Marketing Practices" in hopes of cracking down on advertisers and certification programs that mislead consumers.

Said Rep. Bobby Rush, chairman:

It's time for residents of Washington, D.C. to stock up on reusable bags. The D.C. City Council unanimously voted in favor of a 5-cent tax on both paper and plastic bags that, if approved in a second vote later this month, would make the District the first city in the U.S. to institute a bag fee.

San Francisco banned plastic bags outright in 2007, and Los Angeles' ban will go into effect in 2010. Several other cities have tried to assess bag taxes, but have not yet been successful: Seattle residents will vote on a 20-cent tax in August, and a measure in New York was blocked. Last month, the Philadelphia City Council voted against a 20-cent tax on bags, citing the recession.

When you turn your old technology over to an e-cycling drive, are you sure that it's in good hands? That's what Pittsburghers may be asking themselves after a recent controversy over an e-cycling drive to benefit the Western Pennsylvania Humane Society.   Basel Action Network, a global pollution watchdog, claims that e-cycler EarthECycle did not responsibly recycle the old technology collected for the event, but instead shipped it overseas to developing countries. However, EarthECycle president Jeff Nixon has stated to other media that the items were recycled in a "legal and moral way."  EarthECycle did not return multiple phone calls from U.S. News. You can read BAN's report here.

Tech-recycling drives for charity, such as this one, are becoming increasingly common - so how can well-meaning consumers keep from getting duped? "It's very difficult for consumers to know," said Sarah Westervelt, e-waste project coordinator at BAN. There are, however, a few characteristics of a responsible e-cycler - and a few questions that consumers can ask the company before they drop off their old monitors and cell phones.

Last week, I broke down the results of the Greendex - National Geographic's second annual worldwide poll of consumers about their attitudes on the environment. Over the weekend, I spoke to WTOP Radio in Washington, D.C. about how the red, white and blue isn't really that green after all - even though it's improving.

It's hard to say what the best part of Memorial Day Weekend is: the opening of the pool, the extra day of weekend, or firing up the grill for some burgers and veggies. Certainly, millions of Americans will be preparing the perfect burger this weekend, using gas, charcoal or electricity. But which type of grill has the smallest impact?

The results are in for National Geographic's second annual Greendex, and they aren't pretty: Though the study found that Americans are slightly greener than last year, we're still coming in at the bottom of the pack. Greendex studied 17,000 consumers in a total of 17 countries to find out their opinions on energy, transportation, food, green products, attitudes towards the environment and sustainability, environmental knowledge. And in the nearly 300 pages of data, there are some obvious conclusions - and some surprises.

President Obama announced new emissions and mileage standards today, pushing the average car to 35.5 miles per gallon by 2016 - a 40 percent cleaner fleet of vehicles on our roads. The plan is based on the stricter auto standards that California has sought under federal clean air laws.

So how big of a deal is this? In today's remarks, Obama stated that the move will save 1.8 billion barrels of oil over the cars' lifetime. This is equivalent to:

• taking 177 million cars off of the road
• all of the oil than we imported last year from Saudi Arabia, Venezuela, Nigeria and Libya combined
• shutting down 194 coal-fired plants
• 5 percent of our oil consumption each year

May 15 is Bike to Work Day, a part of National Bike Month, and an annual awareness drive for area bike associations to show commuters just how easy it can be to ditch their cars and subway passes. If Bike to Work Day will be your first time - or if the sight of other bicycle commuters inspires you - the first step to becoming a bicycle commuter (assuming you already have a bike and a helmet, of course) is to plan your route.

It seems easy - just use the same streets your car takes, right? Not quite. While the route you drive may be the most efficient, it's often not the best for you when you downsize to two wheels. Here are some tips for planning your bicycle commute:

Eating local - the movement that encouraged people to purchase their food from small, local farms with sustainable practices - is getting a major corporate makeover. Huge food companies are rebranding local food to include food produced near their processing plants, even though it's still shipped out to your grocery store a thousand miles away. Is the locavore movement losing its soul?

Green moms take care of their kids and the planet. In honor of Mother's Day, here are some tidbits from eco-friendly mom bloggers around the country:

Enviromom, on recycling and arts & crafts: "We have a basket of recyclable items in our playroom that the kids refer to as the reuse bin full of egg cartons, empty food boxes, cardboard toilet paper rolls, bottle caps, etc. The reuse bin is constantly in use because that stuff can become whatever the kids dream of."