Nearly 1 million people in the United States are living with multiple sclerosis, a figure that surprised even researchers when it was published in 2019. That landmark estimate, funded by the National Multiple Sclerosis Society, was more than double the previous count of roughly 400,000, largely because earlier methods had undercounted cases. Each year, roughly 9,500 to 10,600 Americans receive a new MS diagnosis.
How the Prevalence Estimate Changed
For decades, the commonly cited number was about 400,000 Americans with MS. That figure came from older studies that relied on limited data sources and smaller sample sizes. When researchers applied newer methods to insurance claims databases and other large datasets, they found the real number was far higher. The revised estimate of nearly 1 million reflects better detection, broader data access, and growing awareness that MS affects a wider range of people than previously recognized.
Who Gets MS Most Often
MS is diagnosed most often between the ages of 20 and 40, though it can appear at any age. Women make up a clear majority of new cases. Between 2015 and 2022, women accounted for roughly 68% to 71% of new diagnoses each year, meaning they develop MS at about two to three times the rate of men. The reasons for this gap are not fully understood, but hormonal and genetic factors likely play a role.
Children can develop MS too, though it’s uncommon. An estimated 2% to 5% of all people with MS first experienced symptoms before age 18. Onset before age 10 is especially rare, occurring in less than 1% of all cases.
Differences by Race and Ethnicity
MS was long considered a disease that primarily affected white Americans, but that picture has shifted considerably. Data from a large Kaiser Permanente study in Southern California found that Black Americans had a 47% higher risk of MS compared to white Americans. Hispanic Americans, by contrast, had about a 50% lower risk, and Asian Americans had an 80% lower risk.
More recent population-level data complicates the picture further. Over the past three decades, MS incidence rates among Black Americans have been the highest of any racial or ethnic group in the country. And incidence among Hispanic Americans, many of whom are recent immigrants, is higher in the US than in their countries of origin. These patterns suggest that environmental factors, not just genetics, influence who develops the disease.
Types of MS and How They Break Down
About 85% to 90% of people with MS are initially diagnosed with the relapsing-remitting form, known as RRMS. This type involves distinct flare-ups of symptoms followed by periods of partial or full recovery. The remaining 10% to 15% are diagnosed with primary progressive MS, which involves a steady worsening of symptoms from the start without clear relapses. Many people with RRMS eventually transition to a secondary progressive phase, where disability accumulates more steadily over time.
The Financial Weight of MS
MS is one of the most expensive chronic conditions in the country. A 2019 analysis estimated the total economic burden at $85.4 billion. Of that, $63.3 billion came from direct medical costs, with prescription medications accounting for the largest share at 54% of direct spending. The average person with MS incurred about $65,600 per year in excess medical costs compared to someone without the disease, and disease-modifying therapies alone averaged $35,154 per person annually.
The remaining $22.1 billion came from indirect costs: lost wages from disability, reduced productivity at work, absenteeism, and the unpaid labor of caregivers. When caregiver costs were included, indirect costs rose to about $22,875 per person per year. Premature death and the inability to maintain full-time employment were the biggest drivers of those losses.
Geographic Patterns Within the US
MS has historically been more common at higher latitudes, both globally and within the United States. Northern states tend to have higher prevalence than southern ones, a pattern researchers have linked in part to lower sunlight exposure and reduced vitamin D levels. That said, the latitude gradient is not absolute. Genetic background, migration patterns, and local environmental exposures all shape regional differences. The overall prevalence is highest among non-Hispanic white populations, but given the rising incidence in Black and Hispanic communities, the geographic picture is becoming more complex than a simple north-south divide.