Infrastructure companies provide some of the most crucial services we use every day. Roads, bridges, power lines, and buildings are all built and owned by infrastructure companies that aren't often household names. And a lot of these companies are predictably profitable year after year. 

Investors interested in buying into this rough-and-tumble world should start with Brookfield Infrastructure Partners (NYSE:BIP)MasTec (NYSE:MTZ), and United Rentals (NYSE:URI), my top infrastructure stocks for December. 

Construction site with lots of operating equipment.

Image source: Getty Images.

The infrastructure stalwart

Brookfield Infrastructure Partners owns a multitude of infrastructure assets in energy, data, freight, and other industries. It's really a financing company for large projects around the world, which could be an investment in telecommunications towers or an LNG export facility, both of which the company has recently acquired. But the end goal is always to generate consistent cash flows from assets acquired. 

Management aims to generate shareholder returns of 12% to 15% long term, in part through a 5% to 9% increase in dividends. It can do that by owning assets that have contracted revenue, which makes them very consistent operating assets. In the current portfolio, the company has an average term of 15 years remaining on contracted cash flows, and that flow of cash drives the dividend growth you see below.

BIP Revenue (TTM) Chart
Data source: YCharts. TTM = trailing 12 months.

A big advantage Brookfield Infrastructure Partners has is the diversity of assets it can acquire around the world. That diversity allows management to deploy capital where it will generate the most cash, which ultimately drives dividend growth long term. 

Powering the world

MasTec is a construction company that builds everything from transmission lines to bridges and sewer systems. If it's a big infrastructure project in the U.S., the company is likely a bidder. 

You can see below that MasTec is generating a stable profit from its well-diversified construction business. And it could grow steadily in coming years as investments in key markets like renewable energy projects and large transmission lines that service them increase across the country.  

MTZ Revenue (TTM) Chart
Data source: YCharts. TTM = trailing 12 months.

Shares of MasTec trade for just 16 times trailing earnings, which is a solid value in today's market. This may not be a high-growth stock or a hot name for most investors, but if you're looking for a profitable company in infrastructure, MasTec is a good one. 

The construction giant

Construction projects large and small count on equipment rented from United Rentals, and that's what makes it a great infrastructure stock. The company has its hands in almost every type of construction business. 

You can see below that the financial results have been strong as well. United Rentals is consistently profitable and has grown revenue over the last half-decade. Results tapered off early during the pandemic, but are coming on strong now. 

URI Revenue (TTM) Chart
Data source: YCharts. TTM = trailing 12 months.

Management recently increased 2020 guidance for total revenue in a range of $8.35 billion to $8.45 billion and expects free cash flow of $2.2 billion to $2.3 billion. That's strong cash flow for a company with just $10.1 billion in debt and a $17.4 billion market cap. And we could see this rental giant grow as construction and infrastructure investment continues to rise. 

A consistent trio

Spending on infrastructure will fluctuate year to year, but Brookfield Infrastructure Partners, MasTec, and United Rentals will be some of the most consistent and most profitable as long-term investment grows. That's why they're my top infrastructure stocks for December. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.