To answer your question, I would encourage you to examine the factors that led to the outbreak of the Civil War in April 1861: controversy over whether states would be admitted as free states or slave states (the issue in the Missouri Compromise of 1820 was that, if Maine was to be admitted as a free state, Missouri would become a slave state to ensure the balance between free and slave states), and the feeling among many Southerners that Northern abolitionists were interfering with slavery, which was the backbone of their crop-based economy. In the North, the economy was based on various industries, especially the textile industry, which was dominant in New England and, ironically, dependent on slave-picked cotton from the South.
In our present day, our economy is far more diverse; though metropolises, such as New York and Los Angeles, as well as smaller cities, such as Charlotte and Austin, have far more vibrant economies than what exists in rural areas. The latter have suffered from an absence of industry, which has led to economic blight and, as a result of persistent hopelessness, drug addiction. This stark imbalance of economic power and influence, particularly with those in rural areas being so deprived of resources, would not lead to a contemporary civil war. After all, those in impoverished towns wouldn't really have the means to fight those in wealthy cities!
It is true that the United States has yet to resolve its race problem, which is foundational. No one knows if this matter will ever be resolved. However, there have been improvements in people's personal attitudes toward those of different races, sexual orientations, religions, genders, and so on. There remain problems of structural discrimination (e.g., inequities in education, discrimination in lending, etc.), but these problems—as important and stark as they are—are still less visible than those which existed during the antebellum years.
It's also important to note that the Southern plantation system was a feudal one—not dissimilar from that of serfdom, which existed in Russia at the same time. Very few white people managed to be plantation owners. Some owned small farms, while many others were poor white people who were also dependent on the plantation system, where some white men found work as overseers. At the bottom of this network, of course, were the black people who were chattel. Though there are still stark class inequities, and it has become noticeably more difficult for people to elevate themselves into a higher economic class, it remains more feasible to do so than it was in the mid-nineteenth century. And no one is dependent on a single industry as many poor white people were on the plantation system.
In sum, the political and economic factors that led to the US Civil War are no longer relevant. While there remain stark divisions in American society, it is highly unlikely that those divisions would lead to a new war.