No connection found yet to Joel, but it sounds like you may not have found this record before:
1870 US Census:
https://familysearch.org/pal:/MM9.3.1/TH-266-11019-39288-39?... name: Mary E Radebaugh
estimated birth year: 1815
gender: Female
age in 1870: 55y
color: White
birthplace: New York
home in 1870: District of Columbia, United States
Household Gender Age Birthplace
Daniel Radebaugh M 60y Pennsylvania
Mary E Radebaugh F 55y New York
Daniel's profession is given as Printer.
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His profession makes Daniel a possible match to the Daniel here:
http://www.archive.org/stream/bookofmarietta00mcdo/bookofmar..."The Marietta Democrat. First issued in August,
1835, by Charles B. Flood, and was sold to Ja-
cob Baughey in 1838. This paper shortly after-
waid failed "and the property was* purchased by
Daniel Radebaugh, Jr.
The Washington County Democrat was first issued
in April, 1840, Daniel Radebaugh, Jr., but con-
tinued for only a short time. In 1844 it was
revived by J. C. C. Carroll, who continued its
publication until after the first of November of
the same year, after which it ceased. "
. . .
http://familytreemaker.genealogy.com/users/n/i/t/Debra-Nitsc...THE MARIETTA DEMOCRAT -- In August, 1835, the above named paper was started by Charles B. FLOOD, who published it until 1838, when Jacob BAUGHEY took charge of it. The paper was ill supported and soon failed, and the material became the property of Daniel RADEBAUGH, Jr. In April, 1840, he issued the first number of "The Washington County Democrat"
THE WASHINGTON COUNTY DEMOCRAT - This paper remained in existence but a short time. In 1844 it was revived by J. C. C. CARROLL, who published it until after the first of November of that year, when it was stopped.
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One possible other indication that your Daniel was a "Daniel Jr." is a Washington, DC business directory
http://archive.org/stream/boydswashingtong1860wash#page/127/...listing a Daniel Radebaugh Jr, as a clerk in the Treasury Dept in 1860