The story of U.S. 1 begins in 1925 with creation of the U.S. numbered highway system (see "From Names to Numbers" at https://www.fhwa.dot.gov/infrastructure/numbers.cfm). During the early years of the automobile era, the Nation's main highways were known by names rather than by numbers. Usually, a private trail association supplied the colorful name-the Atlantic Highway, Lincoln Highway, the Jefferson Highway, the Pacific Highway, the Old Spanish Trail, and Yellowstone Trail, just to cite a few-and then served as a chamber of commerce promoting improvement and use of the route. By the mid-1920's, however, the hundreds of named trails had become a confusing jumble for motorists. The State highway agencies, therefore, asked the U.S. Bureau of Public Roads (BPR) for help in finding a solution.

A the time, BPR was part of the Department of Agriculture. Therefore, on March 2, 1925, the Secretary of Agriculture appointed the Joint Board on Interstate Highways, which consisted of 21 State highway engineers and three BPR engineers. E. W. James, BPR's Chief of Design, was the secretary and guiding spirit. The Joint Board worked with the States to identify the main interstate roads and create a method of numbering and signing them as part of a "U.S." highway system. East-west roads were given even numbers; north-south roads, odd. Transcontinental and main east-west roads were assigned two-digit numbers ending in zero (U.S. 20, U.S. 30, etc.), while the main north-south routes carried numbers ending in one (U.S. 1, U.S. 11, etc.) or 5. To avoid using "zero" as a route number, the Joint Board used U.S. 2 along the Canadian border.

During the named trail era, the East Coast had several north-south routes along the entire coast or part of that distance, including the Atlantic Highway (Fort Kent, Maine, to Miami, Florida), the Dixie Highway (Sault Ste. Marie, Michigan, to Miami, Florida, with an eastern division through Jacksonville, Florida, and Savannah, Georgia), and the South Atlantic Coastal Highway (Jacksonville to Wilmington, North Carolina). The routes overlapped in some areas (for example, in eastern Florida), but diverged in others--and they all wanted to be part of the main East Coast highway.

Mr. James, in a reminiscence written on February 21, 1967, described how he selected the route for U.S. 1:

I got at once in touch with [Paul Sargent, head of Maine's road agency] on my proposed numbering scheme, putting pressure on my proposed Route No. 1, which I suggested as the first route along the Atlantic side of the U.S.A., following as far as possible the old, historic Falls Line roads. As soon as I mentioned the Falls Line Route Sargent said he was with the whole idea, and that the Falls Line Route really began up in Maine, at Fort Kent on the Canadian border. It was fairly distinct to Boston and Providence, where it headed Narraganset Bay; somewhat indistinct to New York, and then along the River Falls Line to Augusta, Georgia. At Trenton the falls of the Delaware, at Conowing the falls of the Susquehanna, at Georgetown (Washington) the Potomac falls, at Frederick, Virginia, the Rappahannoch, at Richmond, the James, at Petersburg, the Appomattox, at Roanoke, N.C., the Blackwater, at Camden, the Santee, and finally at Augusta, Ga., the falls of the Savannah. At that point the coastal plain becomes so broad and flat that the falls line disappears and at Jacksonville, Florida the road follows the coast, now, to Key West. Sargent knew his colonial geography and said he was with my proposals all the way.

The historic fall line was the farthest point west a cargo ship could go before reaching the rapids. At that point, cargo had to be transferred to wagons, so docks, warehouses, taverns, and eventually cities, developed along the fall line.

When the Joint Board issued its report in October 1925, U.S. 1 was included:

Route No. 1 - From Fort Kent, Maine, to Houlton, Bangor, Rockland, Brunswick, Portland, Portsmouth, New Hampshire, Newburyport, Massachusetts, Boston, Providence, Rhode Island, Narragansett Pier, New London, Connecticut, New Haven, Bridgeport, New York City, Jersey City, New Jersey, Newark, Trenton, Morrisville, Pennsylvania, South Langhorne, Philadelphia, Oxford, Bel Air, Maryland, Baltimore, Washington, D.C., Alexandria, Virginia, Fredericksburg, Richmond, Petersburg, Henderson, North Carolina, Raleigh, Rockingham, Cheraw, South Carolina, Columbia, Aiken, Augusta, Georgia, Swainsboro, Waycross, Jacksonville, Florida, St. Augustine, Miami.

The route followed the Atlantic Highway to a large extent. The Web site North American Auto Trails (http://academic.marion.ohio-state.edu/schul/trails/trails.html) depicted the route of the Atlantic Highway:

• Maine: Fort Kent, Houlton, Calais, Ellsworth, Bangor, Portland
• New Hampshire: Portsmouth
• Massachusetts: Salem, Boston
• Rhode Island: Providence, Westerly
• Connecticut: New London, New Haven, Bridgeport
• New York: New York City
• New Jersey: Jersey City, Newark, Trenton
• Pennsylvania: Philadelphia
• Delaware: Wilmington
• Maryland: Baltimore
• Washington DC
• Virginia: Alexandria, Fredericksburg, Richmond, Petersburg
• North Carolina: Henderson, Raleigh, Southern Pines, Rockingham
• South Carolina: Cheraw, Columbia
• Georgia: Augusta, Savannah, Brunswick
• Florida: Jacksonville, St Augustine, Daytona Beach, West Palm Beach, Miami

The site added that the corresponding U.S. highway was U.S. 1 "except from Augusta to Jacksonville."

Because the roads, including U.S. 1, were owned by the States, not the Federal Government, the Secretary of Agriculture sent the Joint Board's report to the American Association of State Highway Officials (AASHO) with a recommendation that the States take steps to put the plan in operation. Over the next 12 months, AASHO considered requests for changes in the routes selected and in the numbering of them. Eventually, though, on November 11, 1926, the State road agencies approved the plan, and U.S. 1 and all the other original U.S. routes became official.

The first AASHO log of United States Numbered Highways described the official routing of U.S. 1 (spellings as in the original):

United States Highway No. 1.
Total Mileage, 2,328

• Maine Beginning at the United States-Canadian International Boundary at Fort Kent via Van Buren, Presque Isle, Houlton, Calais, Ellsworth, Bangor, Belfast, Rockland, Bath, Brunswick, Portland, Biddeford, Kittery to the Maine-New Hampshire State line north of Portsmouth.
• New Hampshire Beginning at the Maine-New Hampshire State line north of Portsmouth via Portsmouth, Hampton, Seabrook to the New Hampshire-Massachusetts State line north of Newberryport.
• Massachusetts Beginning at the New Hampshire-Massachusetts State line north of Newburyport via Newburyport, Boston, North Attleboro to the Massachusetts-Rhode Island State line north of Pawtucket.
• Rhode Island Beginning at the Massachusetts-Rhode Island State line north of Pawtucket via Pawtucket, Providence, Apponaug, Allenton, Wakefield, Westerly to the Rhode Island-Connecticut State line west of Westerly.
• Connecticut Beginning at the Rhode Island-Connecticut State line at Westerly via Stonington, Mystic, Groton, Flanders Village, Saybrook, Westbrook, Clinton, Guilford, Branford, New Haven, Milford, Bridgeport, Southport, Norwalk, Stamford, Greenwich to the Connecticut-New York State line at Port Chester.
• New York Beginning at the Connecticut-New York State line at Port Chester via New Rochelle, New York City to the New York-New Jersey State line north of Jersey City.
• New Jersey Beginning at the New York-New Jersey State line north of Jersey City via Jersey City, Newark, Elizabeth, New Brunswick, Princeton, to Trenton on the New Jersey-Pennsylvania State line at the Delaware River Bridge.
• Pennsylvania Beginning at the New Jersey-Pennsylvania State line opposite Trenton via Morrisville, Oakford, Philadelphia, Media, Kennett Square, Oxford, Nottingham to the Pennsylvania-Maryland State line south of Nottingham.
• Maryland Beginning at the Pennsylvania-Maryland State line south of Oxford via Rising Sun, Bel Air, Baltimore to the District of Columbia line.
• District of Columbia Beginning at the Maryland-District of Columbia line via Washington to the District of Columbia-Virginia line.
• Virginia Beginning at the District of Columbia-Virginia line via Alexandria, Fredericksburg, Richmond, Petersburg, South Hill to the Virginia-North Carolina State line north of Pashchall.
• North Carolina Beginning at the Virginia-North Carolina State line north of Pashchall, via Norlina, Henderson, Raleigh, Sanford, South Pines, Rockingham to the North Carolina-South Carolina State line north of Cheraw.
• South Carolina Beginning at the North Carolina-South Carolina State line north of Cheraw via Camden, Columbia, Lexington, Batesburg, Aiken to the South Carolina-Georgia State line at Augusta.
• Georgia Beginning at the South Carolina-Georgia State line at Augusta via Wrens, Swainsboro, Baxley, Waycross to the Georgia-Florida State line south of Folkston.
• Florida Beginning at the Georgia-Florida State line south of Folkston, via Jacksonville, St. Augustine, Daytona, Titusville, Melbourne, Fort Pierce, West Palm Beach, Fort Lauderdale to Miami.

After AASHO adopted the U.S. numbered highway system, the Department of Agriculture's Office of Information Press Service issued a series of press releases introducing the public to the new network and highlighting the main routes. One of those press releases, marked "Released for Publication, Sunday, October 9, 1927," was headed:

UNITED STATES ROUTE NO. 1 IS A HIGHWAY OF HISTORY

It began:

Stretching from end to end of the thirteen original colonies, from Fort Kent, Maine, to Miami, Florida, the connecting sections of the Atlantic Coast Highway known as United States Route No. 1 have formed a highway of history for three hundred years. Washington traveled it repeatedly in peace and war. Now the 94-mile section between New York and Philadelphia carries a heavier average traffic than any other road of equal length in the world. Route No. 1 connects New York, Princeton and Philadelphia, the three cities at which the capital was established in the early years of the Republic, with Washington, the final choice; and it passes near or through nearly all of the Revolutionary battlefields and many of those of the Civil War. It grew from blazed footpaths of the settlement era to its present condition which the Bureau of Public Roads of the United States Department of Agriculture reports as surfaced for 84 percent of the distance, graded but unsurfaced for 15 percent, and unimproved for less than 1 percent. Work is proceeding on the less improved sections.

The motorist traveling the road today is reminded frequently of the life and customs of the early days by the old inns which have survived the passage of time, and which now boast - in many cases with truth - of having sheltered the Father of his Country.

A Great Industrial and Tourist Route

Much more than mere chance governed the location of United States Route No. 1. The fact that it follows the “fall line” from New Jersey to Georgia has both a physical and an historical reason. Along this line - the ancient shore line of the continent - the Atlantic Coast rivers tumble down out of the hills into the coastal plain. This physical fact influenced the location of Trenton, Philadelphia, Baltimore, Washington, Richmond, Raleigh, Columbia, and Augusta, all situated at the head of navigation on their respective rivers.

Colonial settlements were made at these points because they were the most inland points to which the colonists could penetrate by boat. Later, as intercourse began and grew between the settlements, the road which is now United States Route No. 1 was blazed as a trail, quickly widened into a wagon road, and early established as the most important inter-colonial road as it is now - from the standpoint of traffic at least - the most important interstate road.

Economically it is important because it connects the great manufacturing and industrial cities of the Atlantic Seaboard, and also because it is the most eastward through road on which all streams are bridged. Consequently, it draws a very considerable local traffic from the peninsular territory to the east.

Connecting semi-tropical Florida with the north-temperate Maine, the road is the principal tourist route from the large eastern cities to the winter resorts of the South and the summer resorts of New England. Its strategic value as a military road in time of war is the conclusive element which stamps this road as the most important, everything considered, in the United States.

Less Than Fifteen Miles Unimproved

According to the Federal bureau's report, the road is now in good condition throughout its entire length, although nearly 363 of its 2,321 miles are still unsurfaced. Between the Canadian line and Ellsworth, Maine, a distance of 338 miles, there are 72 miles of earth road, the remainder being improved with surfaces of gravel or higher type.

From Ellsworth through the large eastern cities to Richmond, Virginia, there is a dustless, all-year pavement for practically the entire distance of 884 miles. South of Richmond, with the exception of a 15-mile unimproved section, there is continuous improvement with sand-clay surfacing or better as far as Augusta, beyond which there are 68 miles of earth road in Georgia much of which is now being surfaced and will be open for traffic by the end of the year.

On the designated route in Florida there are 112 miles of earth road. It should be explained, however, that the road in this State follows a new location which eliminates a number of railroad grade crossings and which will be rapidly improved. Until this improvement is completed travelers are using an alternate parallel route which is surfaced throughout.

The present condition of the road, classified according to types of improvement, is indicated by the following tabulation:

Summary of Improvement of United States Route No. 1

Type of Improvement	Miles
City streets	203
Hard-surface pavements	1,062
Gravel, sand-clay and similar surfaces	683
Graded and drained earth roads	348
Unimproved roads	15
Bridges	10
Total	2,321

The complete press release can be found here.

In 1938, Florida opened the improved Overseas Highway to Key West. At the State's request, road, AASHO approved extension of U.S. 1 to Key West on June 28, 1939. Thus, the route reached its full length: Fort Kent to Key West, 2,446 miles.

Over the years, the States have improved their segments of U.S. 1, often by building bypasses of the cities and towns the original roadway passed through on "Main Street." When they did so, they shifted the U.S. 1 designation to the new roadway. In some locations, the U.S. 1 designation has moved several times, and in some cases onto the parallel I-95 built since the 1950's.

The most recent log of U.S. 1, published by the American Association of State Highway and Transportation Officials in 1989, lists the route as 2,593 miles long.

A couple of books have been published in recent years about U.S. 1, both organized by a tour of the route:

• Genovese, Peter, The Great American Road Trip: U.S. 1 Maine to Florida, Rutgers University Press, 1999.
• Malcolm, Andrew H., and Straus III, Roger, U.S. 1: America's Original Main Street, St. Martin's Press, 1991.

Wikipedia has a lengthy article on U.S. 1 (http://en.wikipedia.org/wiki/U.S._Route_1).