Amanda,
So far I have found two lines of Gerths coming from Prussia. They may be brothers or even cousins. If you would like to email me I can send you some info on my Gerth family and a little on others. sharon_moeller@hotmail.com
I have copies of census records in Illinois that list several Gerth family members. Christian Gerth was born in Prussia about 1800. He sailed for about 22 years before settling in Illinois with Anne or ALice Day from Pennsylvania. She was born about 1818. I'm stuck there and haven't gotten into the Day family yet, although I now have many "honorary" cousins. Keep in touch.