He died in 1876 and is buried with his family at the Scottish Cemetery in Caledonia, Illinois. 
NOTE: Greenlees are sometimes listed with an S and sometimes not, even in the same family. I'm just listing them all as Greenlees.
↑ Original data: Scotland, Births and Baptisms, 1564-1950. Salt Lake City, Utah: FamilySearch, 2013
Name: Peter Greenlies
Baptism Date: 7 Sep 1799
Baptism Place: Killean and Kilchenzie,Argyll,Scotland
Father: James Greenlies
Mother: Mary Clark
FHL Film Number: 1041070
↑ Original data: Scotland, Marriages, 1561-1910. Salt Lake City, Utah: FamilySearch, 2013.
Name: Peter Greenlees
Marriage Date: 3 Mar 1825
Marriage Place: Campbeltown,Argyll,Scotland
Spouse: Martha Ferguson
FHL Film Number: 1041005
↑ "New York, New York, Index to Passenger Lists, 1820-1846," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:K84H-Z6X : 12 March 2018), P Greenless, 1842; citing NARA microfilm publication M261 (Washington, D.C.: National Archives and Records Administration, n.d.); FHL microfilm 350,241.
"United States Census, 1870," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M6W1-VXN : 12 April 2016), Peter Greenlees in household of John Ralston, Illinois, United States; citing p. 7, family 55, NARA microfilm publication M593 (Washington D.C.: National Archives and Records Administration, n.d.); FHL microfilm 545,793.