If you're striving for financial independence, one thing you should do is build up streams of passive income. Passive income is an excellent way to make your money work for you so you can make money when you sleep.

One of the easiest ways to build passive income is by investing in dividend stocks. Dividend stocks come in all shapes and sizes. Some companies pay out more dividends relative to earnings, while some yield higher relative to the share price. thforthe but come with added risk. Others have a long history of increasing their dividend payouts.

One company that has increased its dividend payout for nearly five decades straight is United Bankshares (UBSI -1.47%). The bank has achieved an impressive history of dividend growth and is a couple of years away from being crowned a Dividend King. Here's what you need to know about this passive income opportunity.

Companies that consistently increase dividends earn this coveted title

Companies with a long history of increasing dividends get special recognition for their accomplishments. Dividend Aristocrats are companies in the S&P 500 that have increased their dividends for 25 consecutive years.

Companies that achieve a longer history of increasing payouts are known as Dividend Kings. These companies have increased their dividend payout for 50 consecutive years and don't have to be in the S&P 500 index to be recognized.

United Bankshares operates regional banks throughout the Mid-Atlantic and Southeast, including Virginia, Washington D.C., West Virginia, Ohio, Maryland, and the Carolinas.

The bank has rewarded investors with 48 consecutive years of dividend increases from the bank. Since it isn't in the S&P 500, United Bankshares doesn't get the Dividend Aristocrat title. However, if the bank can maintain increases for two more years, it will finally get the recognition it deserves as a Dividend King.

Here's United Bankshares' secret to growth

The secret to United Bankshares' long history of dividend increases is its growth through acquisitions. Since 1982, the bank has acquired 33 regional banks throughout the Mid-Atlantic and Southeastern United States. 

The bank is strategic about these acquisitions, targeting high-growth metropolitan areas and stable, rural markets to build out its footprint. That bank is always looking for further expansion opportunities.

In the past couple of years, it closed deals to acquire Carolina Financial Corporation and Community Bankers Trust Corporation, improving its foothold in the fast-growing Carolinas and adding to its presence in Washington D.C., Maryland, and Virginia. 

Bank tellers help customers at the front desk.

Image source: Getty Images.

The bank's capital position is strong

United Bankshares' strong balance sheet and capital management make it an attractive dividend stock. At the end of the third quarter, the bank sits on nearly $1.4 billion in cash and cash equivalents. 

It focuses on holding high-quality, diversified loans in its portfolio. Residential mortgages make up 13.4% of its total portfolio, followed by retail commercial real estate at 7.1%, personal auto loans at 6.4%, and hotels at 4.7%. Its consumer loans are high quality, with an average weighted FICO score in its consumer portfolio of 746. 

What's next for the bank

As loan pipelines remain strong, management expects loan growth to be in the mid to high single digits in the fourth quarter. The bank also benefits from the Federal Reserve's aggressive interest rate increases. This year the bank's net interest income (NII) is up nearly 16%, and it expects growth to continue in the fourth quarter. 

The bank expects full-year NII to be between $890 million and $895 million. It has raised this forecast multiple times as interest rates keep rocketing higher. In March, the bank forecasted full-year NII of $780 million to $800 million. 

United Bankshares has accomplished 48 consecutive years of dividend increases because of its strategic acquisitions and stellar capital management. With a 3.4% dividend yield and two years from being crowned a Dividend King, United Bankshares is an excellent dividend stock you can add to your portfolio today.