The North and South fought the Civil War for many reasons, some of which were the same and some of which were different.

 It restates the question without providing any additional information.  It doesn’t tell the reader where your paper is heading.  A reader of this weak thesis might think, “What reasons? How are they the same? How are they different?” Ask yourself these same questions and begin to compare Northern and Southern attitudes  Push your comparison toward an interpretation.

While both sides fought the Civil War over the issue of slavery, the North fought for moral reasons while the South fought to preserve its own institutions.

 There is a reason for the war and some idea of how the two sides disagreed over this reason.  But…this thesis is vague. You need to characterize the differences more precisely.  You need to really capture the argument in your paper and synthesize it in your thesis

While both Northerners and Southerners believed they fought against tyranny and oppression, Northerners focused on the oppression of slaves while Southerners defended their own right to self-government.

 Presents a way of interpreting evidence that illuminates the significance of the question.  There isn’t one right answer; there are only strong and weak thesis statements and strong and weak uses of evidence.  Underline your thesis in your introductory paragraph

Through its contrasting river and shore scenes, Twain’s Huckleberry Finn suggests that to find the true expression of American democratic ideals, one must leave “civilized” society and go back to nature. Although freedom made life better in general for African-American women, freedwomen may have lost some of the power they had held in the family under slavery because freedom subjected them to the patriarchal domination of a sexist society. Legal disfranchisement did not begin until twelve years after the end of Reconstruction, for it took an economic downturn in the South and the coming of age of the first generation of southern African Americans born into freedom to trigger legal efforts to keep blacks away from the polls. Even though Jacksonian Democrats failed in their self-appointed roles as the guardians of the United States Constitution and individual liberty, they achieved great success in strengthening political democracy and the equality of economic opportunity.