There are several reasons why nurses' caps, along with the rest of the uniform, began to disappear in the 1970s. As nursing became more professionalized, nurses wanted to identify more with doctors and other professionals who wore no uniform. At the same time, hospitals started employing ward aides and nursing assistants, who were also outfitted with caps, and subsequently the authority of the graduate nurse's cap was eroded.
In the 1960s to 1980s, hospital schools of nursing gave way to community college and university schools. The apprenticeship system of teaching, with its ritualized progress through the ranks, no longer dominated nursing education, and thus the cap lost much of its symbolic meaning as a signifier of achievement at various levels.
Male nurses have never worn caps. In recent years nursing leaders have tried to encourage more men to enter nursing, and sex-specific uniforms conflict with the larger goal of attracting men to the profession.