If You Don’t Think European Jews Were Always White in the US…
I was a child in Florida in the early 1960s. The Supreme Court had ruled against segregation and school prayer, but Southern schools resisted both changes. When I spoke up in class to protest the morning recital of the Lord’s Prayer, my teacher pointed to one of my classmates, a blond friend, and said, “John’s Jewish, and he doesn’t object. Why do you?” But when I spoke up to protest segregation, there were no black people for her to point to.
During Jim Crow, there was a very simple test for race. Did you use toilets and drinking fountains and schools for whites? Almost all Jews did. Americans commonly assumed Jews were white. The idea of a black Jew was so novel that Time magazine ran a story in 1960 about Sammy Davis Jr. titled “Religion: Jewish Negro”. (He was not the first black American Jew, of course. See The Black Jews of Harlem and Wentworth Arthur Matthew.)
…the antebellum South was relatively free of antisemitism. Not only were the first U.S. senators of Jewish descent southerners, but many southern Jews held other political offices at the state and local levels, and Louisiana produced the first elected Jewish lieutenant governor in American history. Allowed to prosper under Dixie’s sun, Jews accumulated wealth (often in mercantile affairs in cities such as New Orleans, Charleston, and Richmond), acquired and occasionally traded in slaves, sometimes became planters, defended the peculiar institution, and prioritized their identities as southerners over their Jewish affiliations. Jews from Sephardic families naturally volunteered for Confederate service in order to defend what they had come to regard as their land and country.
Junius Rodriguez provides more context in The Historical Encyclopedia of World Slavery:
A few Jews even became prominent slaveowning planters in the Old South … as successful as these Jewish Southerners were by Southern standards, they represent a very tiny percentage of the 20,000 Jews residing in the antebellum South who could, or would, ever aspire to own a slave. About 5,000 Jews owned one or more slaves — about 1.25 percent of all the slaveowners in the antebellum South.