Final answer:
Social factors such as women entering the workforce and advancements in birth control contributed to women outnumbering men in the mid-thirties.
Step-by-step explanation:
Beginning in the mid-thirties, there were several social factors that contributed to the reason why women outnumbered men. One factor was the increasing number of women entering the workforce. As more women started working for wages in various industries, they became more economically independent, which led to changes in their societal roles and expectations. Additionally, advancements in birth control and the availability of information about family planning allowed women to have more control over their reproductive choices, leading to a decline in birth rates. These social changes, along with greater gender equality in marriages, contributed to the shift in the population ratio.