The original six naval bases.

[wausaubob]

I believe during the founders era they created 6 naval bases. They were in Portsmouth, Boston, Brooklyn, Philadelphia, Washington D.C., and Norfolk. By May 1862 the US had them all under control. In addition the merchant services facilities of New Orleans were available to the US. New Orleans was not a ship building center, but it seems probable that the facilities to repair and resupply a ship would be helpful in building a ship. By 1860 there was an additional base at Mare's Island near San Francisco.
The fact that the US retained these facilities had to be a fact to be considered in Britain.

 

[Stryker65]

Would Cairo count as well? It wasn't a Naval Station until the war, nor important to Britain, but it was certainly a major naval hub in 1862.

 

[wausaubob]

Would Cairo count as well? It wasn't a Naval Station until the war, nor important to Britain, but it was certainly a major naval hub in 1862.

On the internal rivers, it was St. Louis, Cincinnati and Pittsburg/Alleghany that mattered. Memphis was no longer a steamboat center by the time of Civil War. Most steamboats could get service in St. Louis and New Orleans. That left the Confederates to try to build ironclads in some very out of the way places, as noted by @DaveBrt .

 

[USS ALASKA]

Once things got rolling...

Union Naval Yards & Stations
Neil P. Chatelain
Gary McQuarrie, Managing Editor

When the Civil War started, there were ten major naval yards and stations across the country. These ranged in size and capacity, with the largest being at the Gosport Navy Yard in Virginia, the Portsmouth Navy Yard in Maine, and the Brooklyn Navy Yard in New York.1,2 These yards built many dozens of warships and converted several hundreds of civilian vessels for wartime service.3 As Virginia and Florida seceded, the Confederates seized both the Gosport Navy Yard and the Warrenton Navy Yard, respectively, but both were recaptured in 1862. Other Southern yards, such as at Key West, Florida, never fell to Confederate forces. Naval facilities expanded during the war, with improvised yards established at Port Royal Sound, South Carolina, to support blockading operations. Yards were also formed at Cairo and Mound City, Illinois to support inland river operations. Naval facilities within the borders of the Confederacy, such as those at Pensacola and Key West, Florida, Port Royal Sound, South Carolina, the Gosport Navy Yard in Virginia, as well as the yards at Cairo and Mound City, were subordinate commands of the squadrons they supported. Navy yards in northern territory coordinated operations with the Navy Department and Secretary of the Navy Gideon Welles and Assistant Secretary of the Navy Gustavus Fox. In northern territory, the station commander typically oversaw recruiting, storehouses, hospitals, marine detachments, ordnance works, and naval construction and received all local requisitions, handling administrative matters and inspecting commissioned vessels in port—they did not have operational control over navy squadrons unless so instructed by the secretary, but often dispatched individual vessels on their own authority to comply with orders from Washington.

The principal naval yards and stations of the Union are summarized below, organized by state, along with some key facts and some additional documentary sources. The summary is not intended to be a comprehensive list of the all of the shipbuilding facilities, yards, and locations utilized by the North during the war.

Full article here - https://civilwarnavy.com/union-naval-yards-stations/

Cheers,
USS ALASKA

 

[USS ALASKA]

And in the opposition corner...

Confederate Naval Yards & Stations
Gary McQuarrie, Managing Editor
Neil P. Chatelain

When the Civil War started, the Confederate states did not have the facilities needed to construct or equip warships.1 The first centers of shipbuilding in the Confederacy were coastal cities that were also significant shipping ports–Norfolk, Charleston, Savannah, Mobile, and New Orleans. Eventually, shipbuilding facilities of various sizes and abilities were spread across many locations on the coasts and rivers of the South. Navy yards are significant facilities where ships can be dry-docked for repairs and extensive alterations, in addition to new construction. Naval stations are facilities where ships can undergo minor repairs and be supplied with fuel and necessary stores.2 When Virginia and Florida seceded, the Confederates captured two of the United States' navy yards, Gosport (Norfolk) Navy Yard, Virginia and Warrington Navy Yard, Pensacola, Florida.3 When the Confederate States Navy was organized, it did not include a specific bureau to oversee construction, so shipbuilding efforts were widespread and poorly coordinated.

During the war, the Confederates had as many as dozen or so major naval yards and stations—these were bound by specified geographical boundaries as prescribed by the Secretary of the Confederate States Navy, Stephen Mallory—the station commander typically oversaw recruiting, storehouses, hospitals, marine detachments, ordnance works, and naval construction and received all local requisitions, handling administrative matters and inspecting commissioned vessels in port—they did not have operational control over navy squadrons unless so instructed by the secretary. After the principal Southern ports were captured by Union forces, naval yards and stations were located in the interior geographically for defensive purposes.

The principal naval yards and stations of the Confederacy are summarized below, organized by state, along with some key facts and some additional documentary sources.1-4 The summary is not intended to be a comprehensive list of the all of the shipbuilding facilities, yards, and locations in the South during the war. A separate list of Confederate shipbuilding locations is available under Resources.

Full article here - https://civilwarnavy.com/confederate-navy-yards-stations/

Confederate Shipyards
Gary McQuarrie, Managing Editor
Neil P. Chatelain

When the Civil War started, the Confederate states did not have the facilities needed to construct or equip warships.1 The first centers of shipbuilding in the Confederacy were coastal cities that were also significant shipping ports–Norfolk, Charleston, Savannah, Mobile, and New Orleans. Eventually, shipbuilding facilities of various sizes and abilities were spread across many locations on the coasts and rivers of the South. When the Confederate States Navy was organized, it did not include a specific bureau to oversee construction, so shipbuilding efforts were widespread and poorly coordinated.1-3

The Confederacy lacked the industrial base of the North and so shipbuilding was undertaken on a much smaller scale. The South's shipbuilding efforts were chronically plagued with shortages of material, machinery, and labor. The overall Confederate strategy of defense also determined the naval policy—the Confederate Navy's efforts concentrated on defending key ports, inlets, bays, and rivers, while cruisers attacked and destroyed Union shipping to divert resources away from the Union's blockading effort. With the South lacking facilities to build large warships, Matthew Fontaine Maury proposed building small wooden gunboats ('Maury gunboats') for river and harbor defense. Secretary of the Navy Stephen R. Mallory was convinced that the South could never match the North in terms of numbers of warships, but that this inequality could be compensated by building ironclads. The Confederacy managed to complete to the point of naming, 34 ironclads, 25 of which were commissioned.4 Except for the very small CSS Manassas in 1862 and the CSS Albemarle in 1864, no Confederate ironclad was sunk or destroyed by Union vessels—most were scuttled or burned to prevent capture. Despite his focus on ironclads, Mallory did develop a plan for a fleet of small wooden gunboats—at least five such vessels were contracted but never completed. Mallory also approved the building of larger wooden-hull gunboats as the war began. Thus, shipbuilding proceeded on multiple avenues but focused on ironclads.1-4

The losses of New Orleans, Memphis, Norfolk, Jacksonville, New Bern, and Pensacola in 1862 were disastrous for the shipbuilding program. In addition to losing vessels under construction, stores and equipment were lost, forcing the building efforts inland where possible—typically safer small river towns or even plots of land adjacent to rivers or inlets where a makeshift yard could be set up and a vessel built and launched without the threat of encroaching Union forces—their exact number is not known because of frequent abandonment or new construction. During the war, the Confederacy converted, contracted for, or laid down at least 150 warships—approximately one-third were steamers converted to gunboats, one-third were wooden gunboats, and one-third were ironclads.1 Numerous armored and wooden vessels were built from the keel up and completed—the remainder (a majority) were either not completed for insufficient supplies of labor, materials, and facilities, or destroyed as a result of having to withdraw from the areas of building for military reasons or to prevent capture.5

The summary is intended to be a comprehensive, but not necessarily a complete list of all shipbuilding facilities, yards, and locations in the South during the war. Vessels constructed in England are not included. A separate list of the principal Confederate Naval Yards and Stations is available under Resources

Full article here - https://civilwarnavy.com/confederate-shipyards/

Cheers,
USS ALASKA

 

[NFB22]

The "Original 6" frigates of the newly formed U.S. Navy were built at Gosport, Boston, Brooklyn, Philadelphia, Portsmouth/Kittery and Baltimore.

 

[ErnieMac]

Not one of the original six, but Warrington Naval Yard in Pensacola was established in the late 1820s. It was seized by secessionist on January 12, 1861, and destroyed when the Confederates evacuated the city in May 1862. The complex was not rebuilt until after the War.

 

[NFB22]

Washington Navy Yard wasn't established until 1799 and even then, it still needed to be constructed. The Marine Barracks (8th & I), located nearby, was established a few years later under the Thomas Jefferson administration.

Hence why one of the original U.S. Navy frigates, the USS Constellation, was built at a private yard in Baltimore.