America's 1857 Layman's Prayer Revival really started in the embers of Charles Finney's Rochester NY Revival where 100,000 were saved.
Charles Finney then began preaching at Park Street Church in Boston for ten months through April 1856. His weekly Revival seminars trained pastors and lay people from every where. Everywhere there was a town, someone was often likely traveling across the nation to hear his messages to take back home. Hundreds of ministries were birthed. Thousands of people continued being saved.
One notable attendee was Jeremiah Lanphier who attended Charles Finney's meetings. It looks like he went from Charles Finney's meeting on keeping Revival to the South Carolina. eight week Revival.