It began with the African slaves in USA in the early days of slavery.
Here are 2 articles that gives a brief overview of the history of the Negro Spirituals:
The following is an article that describes in short the origin of the Negro Spirituals, which was a way of communicating and raise good spirit between the slaves on the cotton fields. This was later adopted in the first black churches, and eventually evolved into a more sophisticated form style called Gospel. At the bottom of the article, there is also a recording sample by Mahalia Jackson of the song I’m On My Way To Canan:
Another article on the history of Negro Spirituals:
This also have links further to Gospel Music and also to how the Salvation Army and Moodey and Sankey made contrubutions to the development of Gospel music.
At last, but not least - The official site of Negro Spirituals and antique Gospel music, which will probably be a very good resource for you to find out a lot on the topic.
Here you will find a lot of history and also some important composers through the time. There are also several free mp3 music samples here, and a shop site (by Amazon) that lists some books and CD's that are related to this.