Why did religious groups develop correspondence education in the 19th-century United States?

In the 19th-century United States, religious groups developed correspondence education primarily to address the challenges of geographical isolation from schools and the needs of dispersed religious congregations.1

This approach allowed organizations to provide structured training to individuals who could not attend traditional institutions. A prominent example is the Chautauqua Lake Sunday School Assembly, which began in 1874 to train Sunday school teachers and church workers. The success of this program, which eventually incorporated a nondenominational course of directed home reading and correspondence study, helped catalyze the broader chautauqua movement across the country.1