The correct answer is D) the city location of a river.
The choice that best describes why the capture of Vicksburg was so significant for the union is because the city location of a river.
After many tries, bloody battles and almost a year of blockade by the Union Army, the city of Vicksburg, Mississippi was captured by the Union troops on July 4, 1863. It was a great victory for the Union because it allowed it to control the Mississippi River and block supplies to other Southern cities.