Thanks for your reply. To answer your questions:
I have absolutely no idea about areas of Germany in the 1800s or now. I have reason to believe that Niedersachsen may be an area in which my ancestors lived only for the fact that I came across several family trees on ancestry.com (to answer your other question about the search engine I am using for world records) that seemed to have many similarities with my ancestor Ferdinand Gross, and the area of Germany was listed as Niedersachsen. This may be inaccurate, but I am trying to start somewhere:)
They did emigrate to the USA, and were listed in both the 1910 and 1920 US Census, listing their arrival date as about 1888. They then settled in the area of Detroit, Mi. They had many children: August, Charles, William, George, Paul, Ida, Edward, Adeline, Henry, Emil, Emma, and Emmaline. Many of these children died very young, or in their first year.
As for Caroline, the wife, I found that she is about six years younger than Ferdinand, (born around 1863, if his birthdate is correct) but did not find an exact year of birth, or a christening record. Their son Paul (1895-1977) Gross went on to marry Zorea(h) Clevenger (of Ohio, USA), and give birth to my paternal grandmother, Sirley Mae (Gross) Rahkola in Detroit, MI.
I appreciate your questions, suggestions, and help. I am still very frustrated with ancestry.com's world search. It lets you choose a region of the world, and brings up possible databases, but none of them are searchable with keywords, and it appears that you have to scroll through all of the records. I am hoping I am missing something, and I am perhaps doing the search incorrectly.