Want a decade of growing passive income? Buy this dividend growth stock and never sell.

Dividend investing is a tried and true strategy for building long-term wealth. It might not be as sexy as buying the hottest high-growth stocks or cutting-edge tech companies, but dividend stocks can be the turtle that drives steady portfolio wealth when looking at a period of several decades. And it takes time. For example, if you buy a 2% dividend stock that grows its dividend per share by 6% per year, it will only yield 3.6% over 10 years. But if the same compounding happens for 30 years, your initial investment will have a return of over 11% at the end of the time period.

This may not seem like much to investors accustomed to fast-paced tech stocks, but you should keep in mind that dividend growth stocks will pay you a cash payment each year that you can choose to keep in cash or reinvest it in a dividend reinvestment program ( DRIPPING). This is the constant combination that can turn a boring stock into a millionaire investment.

Maybe the perfect dividend growth stock is Lockheed Martin (LMT -1.26%). The aerospace and defense contractor has grown its dividend payout at a steady rate, leading to a total return (including dividends) of nearly 5,000% over the past 30 years. Here’s why you should buy this dividend growth stock and never sell.

Lockheed Martin: The First Aerospace Defense Contractor

To understand Lockheed Martin, one must understand the defense and aerospace government contracting business. Typically, the US government will make a proposal for a defense technology or system (eg, a fighter jet) that private companies can bid on. There will also be subcontracting and the ability to sell these products to US allies. Once these contracts are in place, they can last for many decades as the company builds, sells and maintains these product platforms.

Lockheed Martin is the largest US defense contractor with a focus on aerospace systems. It is the prime contractor for the F-35 fighter jet, which is the current generation fighter jet that the US government has been spending hundreds of billions on over several decades. As one of the oldest defense contractors with a reputation for technological innovation, Lockheed was able to secure the F-35 deal over competitors such as Boeing.

In addition to aerospace, Lockheed also has programs for space exploration, rockets and mission systems. All four segments are profitable for Lockheed, generating a combined operating income of $8.5 billion over the past 12 months. With long-term deals in place under these programs, Lockheed Martin has a massive $158 billion in stock that will provide predictable earnings for many years to come.

Predictable dividend growth

Dividend growth is fueled by earnings growth. Lockheed Martin has a predictable increase in earnings because of these long-term government contracts. Let’s use free cash flow per share and compare it to Lockheed’s dividend per share.

Free cash flow per share has grown 204% over the past 10 years at Lockheed Martin. This is the fuel for increasing dividend payments. No cash flow and no dividends can be paid. It’s that simple. Along with this increase in cash flow, Lockheed’s dividend per share has grown 127% over the past 10 years. Interestingly, cash flow growth has far outpaced dividend growth for Lockheed, which should tell investors that the company could have increased its dividend payout faster than it actually did.

With free cash flow per share of $28.46 over the last 12 months and a dividend per share of just $12.45, Lockheed Martin can continue to grow its dividend for many years, even if free cash flow growth per action stagnates. However, as discussed above, these long-term contracts make it extremely unlikely that Lockheed’s earnings will stop growing anytime soon.

LMT Dividends per share (TTM) data by YCharts

Don’t forget share buybacks

The cherry on top of Lockheed Martin’s dividend increase is the company’s stock buyback program. Stock buybacks decrease the number of shares of stock, meaning you have fewer shares to pay dividends on. This makes it easier — all else being equal — for a company to continue increasing its dividend per share. Lockheed has been buying back shares for years, with shares outstanding down about 25% over the past 10 years. As this continues, the dividend per share you get as a remaining shareholder should continue to grow as well.

Right now, Lockheed Martin stock has a dividend yield of just 2.1%, which doesn’t look very appetizing. However, with its history of dividend growth, it can be a huge winning stock for investors looking to buy and hold for many decades.