[or-roots] Naturalization question

[Steve & Ronda Howard]

Since the list is slow, I'm going to ask a non Oregon question, in the hopes
that some of you with way more genealogy knowledge can help me.
I am looking in the City of Chicago Voter Registration for 1888.  My
husband's immigrant great grandfather is listed.  

1888 Chicago Voter's Registration:  Residence - 204 North Av, De Beer Edw,
Nativity - Germany, Color - White, Term of Residence - Precinct 4 mos,
County 20 yrs, State 20 yrs, Naturalized yes, No date or place of
naturalization, By Act of Congress Yes, Qualified Voter yes, Date of
Application to be Registered Oct. 9, 1888, voted no

My question is does anyone know what Act of Congress means?  Most all the
rest of the immigrants on this page were naturalized.  It gives their date
of papers and the name of the court.  But my guy just has a yes in the
naturalized box and a yes in the Act of Congress box.

Thanks!
Ronda

http://content.ancestry.com/iexec/?htx=View&r=an&dbid=5991&iid=cvr_30-1775_0
0000088&fn=&ln=DeBeer&pid=27406 for Ancestry subscribers