During the American Civil War, 25 states remained in the Union at some point during the war, with 23 at the very start in 1861 and additional Union states admitted as the war went on.

Core answer

  • At the outbreak of the Civil War in 1861, the Union consisted of 23 states that did not secede.
  • Over the course of the war, additional states (like West Virginia and Nevada) joined, bringing the total number of states aligned with or counted in the Union side to 25 by the war’s later years.
  • Four slaveholding “border states” (Delaware, Maryland, Kentucky, Missouri) never seceded but are often discussed separately because they were slave states that stayed in the Union.

Quick Scoop: context in plain language

When people ask “how many states remained in the Union,” they are usually talking about the Civil War split between Union and Confederacy in the 1860s. At that time, 11 Southern states formed the Confederacy, while the rest stayed in or were admitted into the Union during the war.

  • The long-term Union-aligned states included the main free states of the North plus the western states and territories such as California and Oregon.
  • The border states were politically divided but never officially joined the Confederacy, which made them strategically crucial and historically distinctive.

Mini breakdown by category

  • Original Union states at war’s start (23) : Northern and some western free states like New York, Pennsylvania, Ohio, Illinois, and California.
  • Border states that remained in the Union (4, later 5 with West Virginia) : Delaware, Maryland, Kentucky, Missouri, and later West Virginia, which split from Virginia and joined the Union in 1863.
  • Later Union admissions during the war : West Virginia (1863) and Nevada (1864) joined as Union states while the conflict was still ongoing.

Simple table of key numbers

Category| Number of states| Notes
---|---|---
Total U.S. states in 1861| 34| Before secession fully unfolded.9
States in Confederacy| 11| Left the Union to form the CSA.5
States remaining in / joining Union (Civil War era)| 25| Includes border states and wartime admissions.5
Union states at very start (1861)| 23| Before West Virginia and Nevada joined.15

TL;DR: If you mean during the Civil War, 23 states stayed in the Union at the start, and a total of about 25 states were on the Union side by the time all wartime admissions are counted.

Information gathered from public forums or data available on the internet and portrayed here.