Congress is based on a single night in January 2018, because people enter and leave homelessness, so talking about a fixed population is difficult.
On that night, 48.9% of all the 552,830 people counted as homeless were white. But 72% of the population, according to HUD, is white (although as they don't break out non-Hispanic white as the Census Bureau does, the 72% may be overstated). So, whites are underrepresented among the homeless. That shouldn't be a surprise. They're also underrepresented among the poor, although they form the largest group of impoverished people.
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African Americans, who make up about 13% of the general population, were 39.8% of homeless people during the count, or triple their percentage of the population. Native Americans are heavily overrepresented among the homeless, being 1.5% of the population but 2.8% of the homeless. It's not as great a degree of overrepresentation as African Americans but still almost double. Pacific Islanders are about 0.5% of the population but 1.5% of the homeless.
Men and boys, at 60.2%, were an enormous percentage of the homeless in comparison to women and girls at 39.1%. Transgender people, while about 0.6% of the population, were 0.7% of the homeless. As for gender nonconforming, they were 0.3% of the homeless, but I've yet to find seemingly reliable statistics that show their percentage of the general population.