I want to thank everyone who responded with tips to my original post. From census and marriage records I now know that my ancestor, Samuel Reeves, emigrated from England to the US between 1850 and 1860. From bible records, I believe he was born in 1818 and that his parents were William and Sarah. LDS records give two conflicting possibilities: a Samuel born to William and Sarah in Tipton and a Samuel born to William and Sarah in Mavesyn Ridware, England.
I've located Samuel, age 43, in a Lowell, Mass, boarding house with Francis (son?), age 17, around 1860 and have tracked him forward in time. I found his marriage in 1860 to Elizabeth Mellor (formerly Healey), his service in the Civil War, and his subsequent residences in Holmesville, Ohio (1870 census) and in Cambridge, Mass (1880 census). A mystery has come up - according to cemetery records, Samuel died in 1890 in Sylvania, Ohio, but was returned to Cambridge for burial. Lucas County, Ohio, Probate and Cambridge Town records have no record of the death. What was Samuel doing in Ohio? Was his visit connected to his residence there in 1870, and could the connection have to do with Francis who disappeared from Lowell? There was a Francis Reeves, age 19, who enlisted in the Civil War from Manchester, NH, around the same time that Samuel enlisted in Lowell. The connection to Manchester, NH, is supported by the birth of Samuel and Elizabeth's (Healey/Mellor) first son, Frederick William Reeves, who was born in 1861 in Manchester, NH.
I still need a definitive tie between Samuel-in-Lowell and the Samuel-in-Manchester-England from the 1851 census. Maybe I can work backward from Francis. Does anyone have information on a Francis (Frank) Reeves, who may have settled in Ohio around 1864-5? The Francis from Manchester, NH, mustered in in 1861 and out in 1864. I'm trying to find a town and/or county of origin in England that could tie him to Samuel Reeves and thereby Samuel to his counterpart in Manchester, England.