As the world increasingly relies on advanced technology — in computing, manufacturing, health care, and more — science and technology are becoming inextricably linked in the U.S. job market. More and more, the jobs with better pay and job security are in STEM — science, technology, engineering, and math — fields.

Some areas — most notably California’s Silicon Valley — have become known across the country and the world for their output of high-tech products and services. There are 15 U.S. major metropolitan areas in which at least 9% of the workforce is employed in a STEM field. 24/7 Wall St. reviewed U.S. cities’ labor forces to determine the cities with the most high-tech jobs.

STEM jobs typically pay significantly better than jobs in non-STEM industries. Regardless of education level, those in STEM fields have a median annual income that greatly exceeds that of non-STEM jobs, according to a study from Pew Research Center.

Many of the STEM jobs found in these cities focus on developing artificial intelligence and automation, which could then replace the work many American workers do. About a quarter of the U.S. labor force, 36 million people, hold jobs that could be made obsolete by advancing technology, according to a study by nonprofit public policy organization Brookings Institution.

Click here to see the 15 cities with the most high-tech jobs.

To identify the 15 cities with the most high-tech jobs, 24/7 Wall St. reviewed metropolitan statistical area (MSA)-level data from the Bureau of Labor Statistics’ (BLS) Occupational Employment Statistics (OES) database for 2017 to find the cities with the highest percentage of total jobs that are classified as STEM-intensive. The most common STEM — science, technology, engineering, and math — job in each MSA was the occupation with the highest location quotient — calculated as the occupation with the highest share in the local labor force relative to the national share — for that occupation. Average wages for STEM jobs and total employment were also derived from the OES data.