There are few stocks that can provide the combination of current income, safety and income growth. Even fewer can provide these characteristics over a decade.But today we'll look at three companies that have increased their dividend payments every year for at least five straight decades. They are members of the "best-of-the-best" group of stocks known as the Dividend Kings.

There are only 18 Dividend Kings. To be a Dividend King, a company must pay increasing dividends every year for at least 50 consecutive years. Dividend Kings have dividend histories long enough to be Dividend Aristocrats twice over.

This requires that a company have an extremely strong and durable competitive advantage, which gives it the ability to grow its dividends safely in the future. 

Safety and income growth are important aspects of any investment, but so is current income. The three businesses analyzed in this article are the three highest-yielding Dividend Kings. Each has a dividend yield of more than 3%.

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1. Emerson Electric (EMR) - Get Report

Emerson Electricoperates in a cyclical industry, but it has been a pillar of stability. It recently celebrated its 125th year as a company, which proves it has stood the test of time.

Emerson Electric has come under pressure from the collapse of commodity prices in the last couple of years. That's because many of its customers are in the oil and gas sector. If that weren't bad enough, Emerson also has had to deal with the strong dollar and slowing economic growth in emerging markets such as China.

Add it all up, and it is no wonder why Emerson's total revenue and adjusted earnings per share declined 9% and 15%, respectively, in its 2015 fiscal year, which ended Sept. 30, 2015.

Fortunately, the company has a plan to get back on track. It has aggressively cut costs and is looking to raise additional cash by divesting underperforming businesses. 

Going forward, Emerson plans to further streamline its business model to focus on only the best opportunities. The company recently divested its network power business for $4 billion. The proceeds of the sale will be used to pay down debt to strengthen the balance sheet.

Conditions have improved in fiscal 2016. Adjusted earnings per share declined only 5% last quarter, and Emerson should be able to return to growth if commodity prices and global economic growth recover.

Emerson has a 3.6% dividend yield and a long history of dividend growth. 2016 will represent the 60th year in a row of increased dividends. Emerson is a very shareholder-friendly company. It expects to generate $3 billion in operating cash flow this year, as much as $2.5 billion of which will be returned to investors via share repurchases and dividends.

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2. Coca-Cola (KO) - Get Report

Coca-Cola is one of the most recognizable and valuable brands in the world. It has a nearly unparalleled brand strength and distribution network in the consumer goods sector, which provides the company with high profit margins.

At the same time, Coca-Cola is at a crossroad. Consumers in the U.S. are drinking less soda than previous generations, as consumers have adopted a more health-conscious approach to food and beverage intake.

In response, Coca-Cola is relying on new products in the U.S. that cater to the health and wellness trend. And, to revitalize growth for its core soda brands, the company is focusing on expansion in new geographic markets.

This strategy is likely to pay off over the long term. Coca-Cola now has a huge portfolio of brands outside its namesake soda, which include Gold Peak and Dasani tea and water.

Separately, Coca-Cola's growth in the emerging markets is taking off. Last quarter, Coca-Cola's adjusted currency-neutral income soared 27% in Latin America.

Coca-Cola has a tremendous track record of dividends. It has paid dividends to its shareholders for more than a century, and, it has a long history of increasing its dividend each year. Coca-Cola has increased its payout for 54 consecutive years.

Its dividend increases often beat inflation, which is great for dividend growth investors. Coca-Cola's last dividend raise was a 6% increase. The dividend yield has inched up to 3.2%, which is attractive given that the S&P 500 as a whole has a 2.1% dividend yield.

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3. Vectren (VVC)

Vectren is an energy holding company. Its businesses include electricity and gas distribution in Ohio and Indiana, as well as energy infrastructure services. Vectren may fly under the radar for many investors, but it has an incredible streak of paying dividends.

Last November, the company raised its dividend by 5.3%, which was the 56th consecutive year of dividend increases.

The reason why Vectren has maintained such a long history of dividend growth is because approximately 81% of the company's profits are derived from its utility business. Utilities have historically been an extremely stable business, as consumers always need gas and electricity.

Furthermore, most of Vectren's utility operations are regulated. This means the company receives approval for annual rate hikes, which virtually ensures modest revenue and earnings growth each year.

Vectren has seen a decline in its fundamentals to start 2016, due to cyclical factors. Earnings per share declined 13% in the first six months of the year, compared with the same period last year, because of the unusually warm weather in the first quarter of the year.

The company still sees 2016 as being a strongly profitable year. Management recently raised its forecast for the full year. Earnings are expected to reach $2.45 to $2.55 per share this year.

Vectren stock is fairly valued, with trailing and forward price-to-earnings ratios of 22 and 18, respectively. These multiples are roughly on par with the S&P 500 index. Vectren has a 3.2% dividend yield, which is better than the average dividend yield for the S&P 500.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.