This is the story that started all the stories in the 163X or Assiti Shard series, including dozens of issues of the Grantville Gazette. It can be read online for free on the Baen Free Library
A natural event, technically solipsistic alien art, sends the town of Grantville, WV back in time from the year 2000 to 1631. This includes an area 6 miles in diameter and includes a fair chunk of coal and natural gas. After a brief foray into the surrounding territory turns up a small band of “mercenaries” raping a farm girl, and torturing her father the mineworkers get a glimpse of the world they’re in. It doesn’t take much after that to lead the town, under the president of the local UMWA, to decide to attempt to start the “American Revolution” early.
This excellent novel takes a light approach to the many problems that come up during the nearly two years of the story. For example, culture shock is shown, most obviously when two of the Abrabanel representatives come to town, but it is shown quickly and the focus moves on. Similarly, the characters are strongly and vibrantly drawn and that vibrancy contributes to drowning out the complexities that the later books delve into.