Infrastructure is vitally important to the world economy. It is defined as the fundamental facilities and systems necessary for an economy to function. It includes roads, electrical grids, and telecommunications towers, among many other facilities. These facilities cost a lot of money to build and maintain. In fact, global infrastructure and capital spending totaled $4 trillion in 2012, and is on its way to an estimated $9 trillion by 2025. Most of this money is spent by governments, but that doesn't mean investors can't profit from growing infrastructure spending. Here are three of the best stocks to invest in to profit from rising infrastructure spending.

Energy infrastructure
One area that will see an enormous amount of private infrastructure spending is energy infrastructure in North America. It has been estimated by ICF International that $641 billion will need to be invested in energy infrastructure in North America through 2035. This is due to the increased output from shale plays, which is pushing down energy prices leading to higher demand.

Pipeline with refinery and setting sun in the distance

Image source: Getty Images.

One of the prime players to benefit from this boom in energy infrastructure spending is Kinder Morgan (KMI -0.04%). Already North America's largest energy midstream infrastructure company, Kinder Morgan plans to spend more than $18 billion over the next five years to build energy infrastructure in the U.S. and Canada. However, as the map below shows, the company sees a lot of potential to build new natural gas infrastructure in the U.S. well beyond that $18 billion.

Source: Kinder Morgan Investor Presentation

While there are dozens of other energy midstream companies in the U.S. with similar growth potential, Kinder Morgan is the clear the leader in the space making it one of the best stocks to invest in the spending boom.

Global trade infrastructure
Investors looking to take a more global and diversified approach should check out Brookfield Infrastructure Partners (BIP -0.21%). The company owns backbone infrastructure around the world that are critical to global trade. For example, it owns a regulated coal terminal in Australia that handles almost 20% of global seaborne coal exports and it transmits electricity to 98% of the population in Chile. Overall, the company also own 6,700 miles of electric transmission lines in North and South America, 6,150 miles of rail tracks in Australia and South America, nearly 2,000 miles of toll roads in South America, and 30 port terminals around the world. Suffice it to say, Brookfield owns a remarkable portfolio of critical global infrastructure.

The portfolio has the company well positioned to benefit from spending growth. First, Brookfield invests its own capital to expand its infrastructure assets and currently has a billion dollar organic growth pipeline. In addition to that, it sees a remarkable potential to acquire assets from governments or other entities, particularly in Europe and Brazil, which will provide growth for Brookfield and capital to these entities that can be reinvested in additional infrastructure assets. For example, in Europe alone it sees medium- to near-term investment opportunities exceeding $50 billion, which includes toll roads, airports, utility networks, telecom infrastructure, and water assets. As Brookfield and others gobble up these assets it will provide capital that can be used to stimulate additional infrastructure investments in Europe.

Communications infrastructure
Another really compelling infrastructure opportunity is communications infrastructure. Mobile data usage is exploding around the globe, with 59% growth in data usage expected this year while global mobile data traffic is expected to grow tenfold between 2014 and 2019. This is leading to a surge in demand for cell towers around the globe. One company that is leading the way to build or acquire these towers is American Tower (AMT -0.10%).

While its name is American, its portfolio is truly global as the company owns more than 87,000 towers in a dozen countries. A bulk of its towers have been acquired over the years from telecom providers, which frees up capital that they are using to build more towers and invest to improve their services. In addition to that American Tower also invests to build its own towers and in the first quarter of 2015, for example, it spent $71 million to complete 23 towers in the U.S. and 621 towers overseas. Given the rapid growth in data the company has an enormous market potential to continue to build and acquire additional communications infrastructure in the years ahead.

Investor takeaway
Trillions of dollars are spent each year on infrastructure. Three of the most compelling areas for investors to profit from this spending is in North American energy, global trade, and communications infrastructure with Kinder Morgan, Brookfield Infrastructure Partners, and American Towers being the best stocks to invest in each trend.