Shadows in the Sun by Chad Oliver (1954)
Chad Oliver was a science fiction fan who never gave up his love of the genre and managed to infuse his science fiction with his other love, anthropology. In Shadows in the Sun, Paul Ellery, a young cultural anthropologist, takes up a challenge he had encountered in his reading:
"A shocking handful of small American vilages have been scientifically studied by cultural anthropologists and rural sociologists. The sample is so small as to be meaningless. The data are hopelessly inadequate. We know as much about the planet Mars as we do about ninety-nine per cent of our own country.
"Look at the towns and villages and whistle-stops of America. Go into them with your eyes open, take nothing for granted, and study them as objectively as you would a primitive tribe. There is no man on this planet who can predict what you may find."
Ellery certainly could not have predicted what he would find as he studied the small Texas town of Jefferson Springs, population 6000. For starters, the town was too perfect. The town appeared typical in every sense; in fact, just about everywhere Ellery looked, there was nothing "untypical" about Jefferson Springs.
And then Ellery discovers something very disturbing about the town's population shift. None of the town's original population remains there. In fact, not a single resident of Jefferson Springs has been in the town for more than fifteen years.
Then came the dark night when Ellery happened to witness a large black shadow blocking the stars, and a globe floats down from that shadow to an isolated ranch and four people emerge from the globe.
Seldom has the "aliens among us" theme been done so well. The aliens seem well-intentioned and non-threatening, but Ellery's study of anthropology tells him that the best of intentions can have severe consequences.
Shadows in the Sun was Oliver's second novel and his first adult book. All of his books, both science-fiction and westerns, are highly recommended.
Below is a link to a 2002 bibliography of Oliver's works. Since then, two retrospective collections of his science fiction stories have been published: A Star Above and Other Stories and Far from This Earth and Other Stories, both NESFA Press, 2003.
If you are not familiar with Chad Oliver's works, you're missing out.