I need your expert advice. I have found records stating that my ancestors immigrated to the U.S. in 1874, arriving at the Port of Baltimore prior to traveling on to Minnesota.

The date of immigration has been past on from generation to generation as Sept 18, 1879, not 1874 as recorded in volume 8 of the Leo Baca reference guide. In fact, one of the children was not even born until 2 years later...

Question: How do I find an accurate date?
Could the error be in the NARA records or just in Leo Baca's guide?

Name: Franz Prokosch
Year: 1874
Age: 37
Place: Baltimore
Source Publication Code: 206.6
Primary Immigrant: Prokosch, Franz
Annotation: Date and port of arrival. Also includes country of origin and name of ship. Place of intended destination may also be provided. Extracted from National Archives Microcopy 255, rolls 1 through 31.
Source Bibliography: Baca, LEO. Czech Immigration Passenger Lists, Volume VIII. Richardson, TX: Author, 1707 Woodcreek, Richardson, TX 75082, 1999. 192p.
Page: 127

Other family members included: Barbara (Wife), Josef, Georg, Barbara (daughter), , Magdalena, Marie

What are your recomendations?

Mark