In this case, the main sentence has an embedded clause at the end:
"<em>I think </em><em>that ’twixt the negroes of the South and the women at the North, all talking about rights, the white men will be in a fix pretty soon</em><em>.</em>" (embedded clause in bold.)
This embedded sentence is <u>complex</u> as it has one independent clause ("<em>...the white men will be in a fix pretty soon.</em>") and a dependent clause ("<em>...that 'twixt the negroes of the South and the women at the North...</em>")
The main sentence presents a simple syntactic pattern: S.V.O. (Subject-Verb-Object), as it contains a mono-transitive verb ("<em>think</em>") which requires a direct object following it ("<em>that...</em>"). The subject of the sentence is the personal pronoun "<em>I</em>". This S.V.O. pattern is present in sentences much simpler, such as "<em>I think this</em>" or "<em>I like that.</em>"
After reading the passage above, one can infer that it belongs to an article or an essay which purpose is to inform the reader about the population boom and its consequences (cause-effect writing). The writer developed the main event in the introduction of the passage and then added supporting sentences about the consequences of that main event. The population is growing in cities such as San Antonio, Phoenix, and Los Angeles and this event has serious effects on the desert environment of these cities mentioned earlier, being the most obvious one the water shortages. The reader can infer all this information thanks to the organization of the text and the words or connectors used. The organization that has been used by the writer is The Casual Chain (one effect is a cause of another effect, which in turn can become a cause of another effect, and so on) and some of the words/connectors chosen to describe the relationship of the events are “result”, “Because…,”, and “concern”.
