We are a leading infrastructure construction company operating mainly throughout North America across a range of industries. Our primary activities include the engineering, building, installation, maintenance and upgrade of communications, energy, utility and other infrastructure, such as: wireless, wireline/fiber and customer fulfillment activities; petroleum and natural gas pipeline infrastructure; electrical utility transmission and distribution; power generation, including renewables; heavy civil; and industrial infrastructure. Our customers are primarily in these industries. Including our predecessor companies, we have been in business for approximately 90 years. For the year ended December 31, 2018, we had an average of approximately 19,000 employees and 380 locations, and offer our services primarily under the MasTec service mark. We have been consistently ranked among the top specialty contractors by Engineering News-Record for the past several years.
We provide our services to a diversified base of customers. We often provide services under master service and other service agreements, which are generally multi-year agreements. The remainder of our work is generated pursuant to contracts for specific projects or jobs that require the construction or installation of an entire infrastructure system or specified units within an infrastructure system.
We seek to grow and diversify our business organically and through acquisitions and/or other strategic arrangements in order to deepen our market presence, broaden our geographic reach and expand our service offerings. For discussion of our recent acquisitions, see Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations - Business," which is incorporated by reference.