Thousands of faculty members went on strike Wednesday at 14 Pennsylvania state colleges and universities — a rare escalation in higher education, but one that reflects increasingly widespread tensions between administrators and their faculties.

The walkout is the first in the nearly 34-year history of the Pennsylvania State System of Higher Education, and is one of a handful of faculty strikes around the country in recent years. The Association of Pennsylvania State College and University Faculties, which represents the faculty members and coaches, has been without a contract since June 30, 2015.

Just this year, professors at two of the nation’s largest public university systems came close to striking; a threatened faculty walkout was just days away at the California State University, and weeks away at the City University of New York, when new contracts were reached. And more labor disputes are expected in the wake of a landmark ruling in August by the National Labor Relations Board that students who work as research and teaching assistants can unionize and demand to be treated as employees.

“Labor issues are far more prominent on the radar screen of higher education than they were 10 or 20 years ago,” said Terry W. Hartle, senior vice president of the American Council on Education, the nation’s largest association of colleges and universities.