“There are several hospitals in our region, like Abington, that will hire nonbaccalaureate nurses but give you a certain number of years to finish the baccalaureate, and some that won’t even interview you without it,” said Gloria Donnelly, dean of the nursing college.

Such policies are limited to a small fraction of the nation’s more than 5,000 hospitals — while no definitive count exists, they tend to be teaching hospitals in major metropolitan areas — but the number is rising fast. Hospital and nursing school officials say most hospitals insisting on bachelor’s degrees began doing so in the last five years, like Abington, a suburban hospital north of Philadelphia, which adopted its policy in 2010.

Surveys show that most hospitals prefer to hire nurses with bachelor’s degrees, though they often cannot find enough. Lawmakers in several states, including New York, have introduced bills that would require at least some hospital staff nurses to have bachelor’s degrees within 10 years, though none have become law.

No matter the type of nursing school, a graduate who passes a national licensing exam becomes an R.N., and for decades, that was the only credential that mattered to hospitals. (Licensed practical nurses, or L.P.N.’s, who take a different version of the exam, can perform fewer functions and are being phased out of hospitals.)

Not long ago, most nurses did not go to college at all, but to nursing schools run by hospitals — including one still run by Abington — that do not confer degrees. As recently as the mid-1980s, half of the country’s registered nurses had started that way. But by then, hospital-based schools were closing in droves, and community college education was becoming the norm.

Still, professional groups and employers continue to push for more education, citing studies linking better-educated nurses to better patient care. Where traditional nursing education focuses on practical skills, students in four-year programs learn more about theory, public health and research.

An added incentive for hospitals is the coveted “magnet” designation, awarded by the American Nurses Association to about 400 hospitals and sometimes featured in their advertising. Among the association’s criteria for magnet status is the nursing staff’s level of education.