#1 1800s Era
Nursing firstly started in Philadelphia in 1700s and later spread throughout the United States. At those times it was not considered as a noble profession rather it was called as a street profession.
#2 1900s Era
Then with the influence of some women like Florence Nightingale people realised that trained nurses are necessary for the proper health facilities. This gave birth to uniforms which was light gowns with white aprons and cloth caps.