Primary Documents

newspapers--memoirs--letters--photographs--maps--miscellaneous--secession

Newspapers

The Historical New York Times Project:  The Civil War Years
Secession Era Editorials Project at Furman University (newspaper editorials leading up to the Civil War)
Rare Civil War Newspapers (for sale, but includes headlines, quotes, and partial graphics)
"A Tough Story" in the Cleveland Plain Dealer May 1861
Selected Articles-Cleveland, Ohio Newspapers 1861-65
US Marine Corps Deserters' Notice (1865)
The Civil War: A Newspaper Perspective (Not available to the general public)

Memoirs

Personal Memoirs by Ulysses S. Grant
Reminiscences of the Civil War by Gen. John B. Gordon
From Manassas to Appomattox by Lt. Gen. James Longstreet (CSA)
Advance and Retreat by Lt. Gen. J. B. Hood (CSA)
The Memoirs, Diary, and Life of Private Jefferson Moses, Company G, 93rd Illinois Volunteers
Civil War Memories of Robert C. Cardin, Company B, 16th Tennessee Infantry

Letters

Letter from General Beauregard reporting the fall of Fort Sumter
Letters from Private Newton Scott of Iowa
POW Letters of Brigadier General Montgomery Corse      
The Butler Letters: Henry Butler to his wife Mary during the Civil War 1862-1865  
The Follett Collection (letters of the Follett family, 3 sons serving in the U.S. Army)
Letter from Captain James W. Grace, white officer of the black 54th Mass. Vol. Infantry 

Photographs and Artwork

Selected Civil War Photographs (searchable index at the Library of Congress)
Valley of the Shadow Images Search (searchable index of photos and illustrations of battles)
Images of Wartime at The American Civil War Homepage
Photographs of 54th Mass. Vol. Infantry (scroll to near bottom of page)
Civil War Cartoons (examples of political cartoons; some are difficult to read)
Civil War Album (modern photographs of battlefields, maps & official reports)
Well-Traveled Images Online Gallery (modern photographs)

Maps

Civil War Maps (searchable index of historical maps at the Library of Congress)
U.S. National Park Service Maps Index (search by interest--Civil War & Battlefield/Military Park)
Perry-Castaņeda Library Map Collection (alphabetical listing of U.S. National Parks & Monuments)
Rare Civil War Map Collection at the University of Georgia Libraries

Miscellaneous (diaries, poems, sermons, legislation, etc.)

Documenting the American South (collection of electronic texts at UNC Chapel Hill)
Documentary Records at The American Civil War Homepage (public and private documents) 
Military History Index at the Library of Virginia (Confederate enlistment records & unit information)
Digital Library and Archives at Virginia Tech (scroll down below photo for listing of documents)
U.S. Sanitary Commission (medical reports, battlefield results, and advice for soldiers)
Income Tax Records of the Civil War Years at the National Archives (article on the first income tax)  
Impression Documentation (Quotes from Soldiers)
Civil War Navies: Official Records (telegrams and reports about the battle at Hampton Roads)
The Official Records of the War of the Rebellion (Commanders' After Action Reports)
A Vast Sea of  Misery (history & guide to USA and CSA field hospitals at Gettysburg)
Confederate States of America Documents (The Avalon Project at Yale Law School)
Civil War Women On-line Archival Collections at Duke University
Civil War Documents (miscellaneous listing at the United States Civil War Center)
Civil War Documents (smaller listing at the Civil War Index)
Clipart (modern clipart as well as historical line drawings)

Secession Related Documents

Virginia Declaration of Rights (1776) prior to Declaration of Independence
The Declaration of Independence (1776)
The Constitution of the United States of America (1787) 
The Constitution of the Confederate States of America (1861)
Comparison of USA vs. CSA Constitutions 
South Carolina Declaration of Secession ( Dec. 24, 1860) 
Georgia Declaration of Causes of Secession (Jan. 29, 1861)
Texas Ordinance of Secession (Feb. 2, 1861)  
Mississippi Declaration of Secession (?)