Waste Management (NYSE: WM) isn't just the industry leader in dumping garbage. It's also the nation's largest recycler, an innovator in generating renewable energy, and the owner of 271 landfills and 107 recycling facilities as of the end of 2011. Here are some recent stats for North America's self-proclaimed leading provider of integrated environmental solutions:

52-Week High $36.85
52-Week Low $27.75
Market Cap $15 billion
CAPS Rating (out of 5) *****

Source: Yahoo! Finance.

It's been a somewhat volatile year for Waste Management's investors, up almost 10% at one point and currently down 0.34%. The drop happened in April when the company reported first-quarter financials. Revenue was up, but earnings per share were lower than expected. The company expected this hit, though, due to higher gas prices and lower commodity costs. It's still a great potential investment for your portfolio, and here are three great reasons.

1. Necessity
The average American produces 1,600 pounds of trash each year and is accustomed to having somebody in a truck take it away for them. Our garbage habits and expectations are unlikely to change anytime in the near future. Because of this, companies like Waste Management are a necessity. This makes it a fairly recession-proof stock, as the stock's positive performance during the bear-market year of 2008 shows.

2. Industry leader
For an industry that's such a necessity, investors might wonder why there are only a few big players out there. The main reason is that this type of business is very capital-intensive to start up, and scale is important.

On the garbage hauling side, the larger a company is, the cheaper it is to get trucks out to you, which means the company can afford to offer more attractive prices in contract bids. On the disposal side, running facilities to sort garbage and recyclables, and even transform them into a renewable source of energy, is expensive.

Waste Management is the industry leader with a $15 billion market cap, bigger than that of both its largest competitors combined: Republic Services (NYSE: RSG) has a roughly $10 billion market cap, and Waste Connections (NYSE: WCN) weighs in at about $3.75 billion. Size matters in this industry, and Waste Management has the definite advantage.

3. Innovation
Waste Management calls itself a provider of integrated environmental solutions. It does more than just haul and dispose of your garbage and recyclables. New technology is allowing the company (as well as its competitors) to explore methods of converting methane gas into electricity. This could end up providing the industry with an entirely new source of revenue, which would be good news for its already happy investors.

Waste Management is an overall great company and investment, and I'm not the only Fool who thinks so. Our newsletters have recommended the company, too. But The Motley Fool has another company that they think is really set to pop this year -- a retail company changing the way people shop in Latin America that'd make a great addition to any portfolio. To read all about our top stock for 2012, just click here.