Final answer:
The largest group of the US population without health insurance consists of individuals in low-paying jobs that do not offer insurance and those below the poverty line not covered by Medicaid. Despite the implementation of the Affordable Care Act, about 31 million Americans remained uninsured in 2020.
Step-by-step explanation:
The largest group of the US population without health insurance includes many individuals from households with income above the poverty line but whose employers do not offer them health coverage. These jobs are often temporary or part-time with low pay. In addition, there are approximately 15 million people with income below the poverty line who are not covered by Medicaid. Despite the introduction of the Patient Protection and Affordable Care Act (ACA), which aimed to increase insurance coverage, approximately 31 million Americans remained uninsured in 2020. The ACA did, however, make it possible for people with preexisting conditions to obtain health insurance, and as a result, the proportion of those without insurance in the US decreased from 20.3% in 2012 to 8.6% in 2020, meaning that around 20 million Americans gained coverage through the ACA.