Since there were still states in this century who allowed marriages that young, it obviously was something that happened. Whether it was the norm or not is a more interesting question.
I was surprised when it was posted that Loretta Lynn got married when she was 14. But I was talking to a neighbor from Loisiana and apparently there are a few girls getting married at very young ages there as well.
At one church I have personal knowledge of, the son of the minister married a 15-year-old.
Again, not to say it was the norm. Also not sure we can compare 1900 to 1850, by 1900 we were well into the industrial period; 1850 was still a different cultural era altogether.
Was this just normal behavior for that time period?