Hmm. Don't know about the 1950s, but according to Hugo P. Leaming (in "The Ben Ishmael Tribe: A Fugitive 'Nation' of the Old Northwest," the opening article in the delightfully quirky Gone to Croatan: Origins of North American Dropout Culture), there was a long-standing nomadic group that followed a triangular annual migration route from Indianapolis up to the Kankakee River south of Chicago, then down to Mahomet, Illinois, and back to Indianapolis in the fall. The group had moved from Kentucky into the "Old Northwest" (what's now Ohio, Indiana and Illinois) in the 1700s, pushed ahead of what mainstream society considered "the frontier" - an earlier nomadic route had Cincinnati near one point of the triangle, but by 1810, they traveled northwest out of Indianapolis in the spring and not east back into Ohio.

They were neither Rom nor Irish-American tinkers, but a kind of "tri-racial isolate" group consisting of the descendants of poor whites, Native Americans (possibly Shawnee) and escaped or freed African slaves (possibly Fulani). They were sometimes identified as gypsies by settlers, but did have some permanent cabins on the route, including some kind of monumental, three-pointed "log mansion" that the patriarch Tom Ishmael used as a winter home in the northern section of the triangle.

The group appears in James Fenimore Cooper's The Prairie, according to Leaming, and shows up in other accounts (Leaming basically claims "Allie" Smith, the inspiration for the narrator of the poem "Little Orphant Annie," as an Ishmaelite) , but didn't leave much of a record of themselves - most were illiterate. The group was overtaken by settlement at the end of the 1800s, beginning of the 1900s. Some of their camps became black neighborhoods in fast-growing Midwestern cities, and the group more or less lost its identity during the rise of the eugenics movement - being considered "degenerates" and racially and genetically impure by mainstream culture, many were institutionalized or worse. (Even Cooper referred to them as "the offcasts of all honest people.")

They did leave some traces - one of Leaming's goals seems to be to draw a line from the Ishmaelites to the precursors of the Nation of Islam - and, speculatively, there might have been some last nomad caravans in the Midwest through the Great Depression years. But this article definitely doesn't go into the 1950s.

Totally apart from that, there are Rom communities in the U.S. (I know of one in South Florida that was the subject of some reporting in the 1990s and early 00s... and some more recent controversies), but they seem to not be living in caravans, but in typical ethnic neighborhoods, occasionally passing as some other ethnicity (in the South Florida reports, they were often mistaken for Latin Americans). So much of the news reporting is flavored by Gypsy stereotypes that it's hard to separate the facts from the story.