100 years of US routes: 1926-2026
Currently, two US routes include ferry segments (US 9 across Delaware Bay and US 10 across Lake Michigan). However, that number was much higher historically: at least 32 US routes once included ferry segments (and the following list may well be incomplete; please let me know if you have any additions or corrections). Also note that -- whereas US 9 and US 10 have one ferry segment each -- the list below shows that historically some US routes had multiple ferry segments. In general, the wider a body of water, the more likely that a US route had to use a ferry to cross it... initially. But already by 1940 more than half of the following ferry segments had been replaced by bridges.
US 2(w): This first example appears to be unique, because rather than the typical ferry (which transports drivers and their vehicles over a body of water), US 2 traffic needed to be transported over land. This was because the segment of US 2 over the Great Divide at Marias Pass (MT) had not yet been completed, so automobiles were loaded onto a rail car "ferry" and the Great Northern Railroad served as the mode of transportation across that segment. That was illustrated on the following 1927 map (this arrangement lasted until 1930):
US 9: This is one of only two US routes that still include a ferry segment. For nearly five decades, the south end of US 9 was on Cape May (NJ), but in 1974 AASHO approved an extension across Delaware Bay via the Cape May - Lewes (DE) ferry.
It should also be noted that US 9 was originally planned to use the Manhattan - Staten Island (St. George) ferry, and the following 1934 atlas erroneously illustrated it that way. The reality was that US routes were not signposted in the NYC area until 1935, and US 9 traffic has always been directed to use the c. 1931 George Washington Bridge (despite what was shown on this map):
US 10: This is the other US route that currently has a ferry segment, which runs across Lake Michigan between Ludington (MI) and Manitowoc (WI). US 10 is the only route that included a ferry segment for the entire first century of the US route system's existence (although for the majority of that time the ferry segment was only "implied", with AASHTO finally "formalizing" the ferry as a part of the US route in 2015).
US 13: Chesapeake Bay ferry from 1943-1964. From US 13's original terminus at Cape Charles (VA), drivers could take one ferry to Ft. Monroe (Old Point Comfort) or a different ferry to Little Creek (which is now in the northwestern part of Virginia Beach city limits). But neither of those ferries were part of US 13 until 1943, which is when the US 13 designation was extended over the Little Creek ferry (and on to a new terminus at Bowers Hill). In 1951 the US 13 ferry from Little Creek went to a new landing at Kiptopeke. In 1964 US 13 was rerouted to utilize the newly-opened Chesapeake Bay Bridge-Tunnel.
Lake Michigan ferry between Milwaukee and Grand Haven (MI) from 1926 to the mid-1930s, and then...
Lake Michigan ferry between Milwaukee and Muskegon (MI) until 1961 (which is when US 16 was decommissioned in Michigan).
Gloucester - Yorktown (VA) ferry (across York River) from 1926-1952 (which is when the Coleman Bridge opened).
Elizabeth River ferry between Norfolk and Portsmouth (VA) from 1926-1931, and also...
Norfolk - Old Point Comfort ferry (across Hampton Roads in VA) from 1926-1930, and then...
Norfolk - Newport News ferry (across Hampton Roads) from 1930-1931. US 17 stopped using any of these Norfolk-area ferries in 1931, when drivers were redirected to use the Nansemond River and James River bridges; see also US 60.
Cape Fear River ferry at Wilmington (NC) from 1926-1929 (when it was rerouted).
US 24: Mississippi River ferry at Quincy (IL) from 1926-1930 (which is when the Memorial Bridge opened).
US 31: Straits of Mackinac ferry between Mackinaw City and St. Ignace (MI) from 1926-1940. (The Mackinac Bridge was not built until 1957, but the US 31 designation was truncated to Mackinaw City in 1940 because US 2 had been rerouted to go through St. Ignace. So the ferry remained operational, but it did not carry a US route from 1940-1957.)
US 36 may have had a Mississippi River ferry at Hannibal (MO). Missouri's official state highway maps from 1927-1932 had symbols for a ferry as well as a toll bridge (this would have referred to the c. 1871 Wabash Bridge; in 1936 auto traffic was moved to the Mark Twain Bridge):
Benicia - Martinez (CA) ferry (across Carquinez Strait) from 1926-1931 (the Carquinez Bridge opened in 1927, but it was not part of the state highway system until 1931).
Wilmington (DE) - Penns Grove (NJ) ferry (across Delaware River) from 1926-1928, and then...
New Castle (DE) - Pennsville (NJ) ferry (across Delaware River) from 1928-1951 (which is when the Delaware Memorial Bridge opened).
US 41: Ohio River ferry between Evansville (IN) and Henderson (KY) from 1926-1932 (which is when the Audubon Bridge opened).
US 45: Ohio River ferry between Paducah (KY) and Brookport (IL) from 1926-1929 (which is when the Cobb Bridge opened).
US 50: Chesapeake Bay ferry between Annapolis and Maryland's Eastern Shore from 1948-1952 (which is when the Chesapeake Bay Bridge opened).
US 51: Mississippi/Ohio River ferry between Cairo (IL) and Wickliffe (KY) from 1926-1938 (which is when the Cairo Ohio River Bridge opened; see also US 60 and US 62).
US 54: Mississippi River ferry at Louisiana (MO) from 1926-1928 (which is when the Champ Clark Bridge opened).
US 58: Elizabeth River ferry between Norfolk and Portsmouth (VA) from 1931-1962 (which is when the Midtown Tunnel opened; see also US 17, US 117, and US 460).
Mississippi River ferry between Cairo (IL) and Birds Point (MO) from 1926-1929 (which is when the Cairo Mississippi River Bridge opened).
Mississippi/Ohio River ferry between Cairo (IL) and Wickliffe (KY) from 1926-1938 (which is when the Cairo Ohio River Bridge opened; see also US 51 and US 62).
Norfolk - Newport News (VA) ferry across Hampton Roads from 1929-1930 (see also US 17), and then...
Ft. Monroe (Old Point Comfort) - Ocean View (Willoughby Spit) ferry across Hampton Roads from 1930-1957 (which is when the Hampton Roads Bridge-Tunnel opened).
Mississippi/Ohio River ferry between Cairo (IL) and Wickliffe (KY) from 1930-1938 (which is when the Cairo Ohio River Bridge opened; see also US 51 and US 60).
Norfork Lake ferry (near Mountain Home AR) from 1944-1983 (which is when the Panther Bay Bridge opened).
Croatan Sound (NC) ferry between Manteo and Manns Harbor from 1951-1957 (which is when the Umstead Bridge opened; see also US 264).
Alligator River (NC) ferry from 1951-1960 (which is when the Warren Bridge opened).
US 65: Mississippi River ferry between Natchez (MS) and Vidalia (LA) from 1935-1940 (which is when the first Natchez-Vidalia Bridge opened; see also US 84).
US 80: Mississippi River ferry between Vicksburg (MS) and Delta (LA) from 1926-1930 (which is when the Old Vickburg Bridge opened).
US 82: Mississippi River ferry at Greenville (MS) from 1932-1940 (which is when the Humphreys Bridge opened).
US 84: Mississippi River ferry between Natchez (MS) and Vidalia (LA) from 1934-1940 (which is when the first Natchez-Vidalia Bridge opened; see also US 65).
US 89: Lees Ferry (near Page AZ) across Colorado River from 1926-1929 (which is when the Navajo Bridge was opened).
US 90: during the first year of the US highway system, motorists had to use no less than eight ferries to get across Mississippi and Louisiana (but that number was gradually reduced to zero by 1935).
Pascagoula (MS) ferry from 1926-1928 (when the original bridge opened).
Biloxi Bay (MS) ferry from 1926-1930 (when the Memorial Bridge opened).
Bay St. Louis (MS) ferry from 1926-1928 (when the original bridge opened).
Rigolets (LA) ferry from 1926-1930 (when the Fort Pike Bridge opened).
Chef Menteur Pass (LA) ferry from 1926-1929 (when the eponymous bridge opened).
Walnut Street ferry across the Mississippi River in New Orleans from 1926-1935 (when the Huey Long Bridge opened).
Atchafalaya River ferry between Morgan City and Berwick (LA) from 1926-1933 (when the Long-Allen Bridge opened).
Sabine River ferry at Orange (TX) from 1926-1927 (when the Memorial Bridge opened).
US 97: Columbia River ferry at Maryhill (WA) from 1926-1962 (which is when the Sam Hill Bridge opened).
Golden Gate ferry between San Francisco and Sausalito (CA) from 1926-1937 (which is when the eponymous bridge opened).
Columbia River ferry between Astoria (OR) and Megler (WA) from 1926-1966 (which is when the Astoria-Megler Bridge opened).
US 117[i]: Elizabeth River ferry between Norfolk and Portsmouth (VA) from 1926-1931 (which is when US 117 was replaced by US 58; see also US 17 and US 460).
US 121[i]: Jacksons Ferry (near Ft. Chiswell VA) across New River from 1926-1931 (which is when the New River Bridge opened).
US 190: Mississippi River ferry between Baton Rouge and Port Allen (LA) from 1934-1940 (which is when the Old Bridge opened).
US 264: Croatan Sound (NC) ferry between Manteo and Manns Harbor from 1951-1957 (which is when the Umstead Bridge opened; see also US 64).
US 322: Delaware River ferry at Chester (PA) from 1936-1974 (which is when the Commodore Barry Bridge opened).
US 460: Elizabeth River ferry between Norfolk and Portsmouth (VA) from 1933-1934 (when it was rerouted); see also US 17, US 58, and US 117).
Research and/or image credits: Tom Fearer; Mike Roberson; Dale Sanderson