The Underground Railroad in Indiana was part of a larger, unofficial, and loosely-connected network of groups and individuals who aided and facilitated the escape of runaway slaves from the southern United States. The network in Indiana gradually evolved in the 1830s and 1840s, reached its peak during the 1850s, and continued until slavery was abolished throughout the United States at the end of the American Civil War in 1865. It is not known how many fugitive slaves escaped through Indiana on their journey to Michigan and Canada. An unknown number of Indiana's abolitionists, anti-slavery advocates, and people of color, as well as Quakers and other religious groups illegally operated stations (safe houses) along the network. Some of the network's operatives have been identified, including