Computers are all around us — from desktops at work and home to smartphones everywhere in between. In fact, about 4 in 5 households own some type of computer. America’s use of technology relies on a large workforce to maintain networks, develop hardware and software, and provide support. In 2014, 4.6 million people worked in information technology (IT).

A new report released today by the U.S. Census Bureau explores trends in IT occupations since 1970 as well as characteristics of the IT workforce. Moreover, it explains how the Census Bureau tracks growing and evolving occupations over time.

The number of IT workers increased tenfold between 1970, when the Census Bureau first recognized IT occupations, and today. When scientists and engineers developed computers, their work was classified into three categories: programming, analyzing and everything else. Other workers performed job activities, which today would be classified as IT occupations. As computers emerged from room-sized machines to personal workstations connected to the internet, the type of IT work diversified. Thus, the classifications for IT occupations needed more detail to categorize the work adequately, and the number of IT occupations expanded to account for the changes.

The figure below illustrates the growth and increasing complexity of IT occupations. Between 1970 and now, the Census Bureau increased the number of IT occupation classifications from three to 12. The largest expansion came during the technology boom in the 1990s when the number of IT workers more than doubled from 1.5 million to 3.4 million. Some of the occupations “born” from the expansion included computer support specialists, computer software engineers, and network systems and data communications analysts.

After the steep rise at the end of the 20th century, the demand for IT workers slowed down compared with the previous decade. However, the number of distinct occupations continued to grow. By 2010, the Census Bureau added four more IT occupations.

The report released today describes the growth and occupational diversity of the information technology workforce in the United States. In addition, the report provides a description of demographic and employment characteristics of IT workers in 2014 using statistics from the American Community Survey.