Seedling miles and the ideal section

The Lincoln Highway Association did not have enough funds to sponsor large sections of the road, but from 1914 it did sponsor "seedling mile" projects. According to the 1924 LHA Guide the seedling miles were intended "to demonstrate the desirability of this permanent type of road construction" to rally public support for government-backed construction. The LHA convinced industry of their self-interest and was able to arrange donations of materials from the Portland Cement Association.^[1]
The first seedling mile (1.6 km) was built in 1914 west of Malta, Illinois; but, after years of experience, the LHA organized a design plan for a road section that could handle traffic 20 years into the future. Seventeen highway experts met between December 1920 and February 1921, and specified:

• a right-of-way 110 feet (34 m) in width
• a concrete road bed 40 feet (12 m) wide and 10 inches (254 mm) thick to support loads of 8,000 pounds (3,600 kg) per wheel
• curves with a minimum radius of 1,000 feet (300 m), banked for 35 mph (56 km/h), with guard rails at embankments
• no grade crossings or advertising signs
• a footpath for pedestrians^[1]

The most famous seedling mile built to these specifications was the 1.3-mile (2.1 km) "ideal section" between Dyer and Schererville in Lake County, Indiana. With federal, state, and county funds, and a $130,000 contribution by United States Rubber Company president and LHA founder C.B. Seger, the ideal section was built during 1922 and 1923. Magazines and newspapers called the ideal section a vision of the future, and highway officials from across the country visited and wrote technical papers that circulated both in the United States and overseas. The ideal section is still in use to this day, and has worn so well that a driver would not notice it unless the marker near the road brought it to their attention.^[1]

United States Numbered Highways

Lincoln Highway marker in Carson City, Nevada

By the mid-1920s there were about 250 National auto trails. Some were major routes, such as the Lincoln Highway, the Jefferson Highway, the National Old Trails Road, the Old Spanish Trail, and the Yellowstone Trail, but most were shorter. Some of the shorter routes were formed more to generate revenues for a trail association rather than for their value as a route between significant locations.
By 1925 governments had joined the roadbuilding movement, and began to assert control. Federal and state officials established the Joint Board on Interstate Highways, which proposed a numbered U.S. Highway System which would make the trail designations obsolete, though technically the Joint Board had no authority over highway names. Increasing government support for roadbuilding was making the old road associations less important, but the LHA still had significant influence. The Secretary of the Joint Board, BPR official E. W. James, went to Detroit to gain LHA support for the numbering scheme, knowing it would be hard for smaller road associations to object if the LHA publicly supported the new plan.
The LHA preferred numbering the existing named routes, but in the end the LHA was more interested in the larger plan for roadbuilding than they were in officially retaining the name. They knew the Lincoln Highway name was fixed in the mind of the public, and James promised them that, so far as possible, the Lincoln Highway would have the number 30 for its entire route. An editorial in the February 1926 issue of The Lincoln Forum reflected the outcome:

The Lincoln Highway Association would have liked to have seen the Lincoln Highway designated as a United States route entirely across the continent and designated by a single numeral throughout its length. But it realized that this was only a sentimental consideration. ... The Lincoln Way is too firmly established upon the map of the United States and in the minds and hearts of the people as a great, useful and everlasting memorial to Abraham Lincoln to warrant any skepticism as to the attitude of those States crossed by the route. Those universally familiar red, white and blue markers, in many states the first to be erected on any thru route, will never lose their significance or their place on America's first transcontinental road.

The states approved the new national numbering system in November 1926 and began putting up new signs. The Lincoln Highway was not alone in being split among several numbers, but the entire routing between Philadelphia and Granger, Wyoming, was assigned US 30 per the agreement. East of Philadelphia the Lincoln Highway was part of US 1, and west of Salt Lake City the route became US 40 across Donner Pass. Only the segment between Granger and Salt Lake City was not part of the new numbering plan; US 30 was assigned to a more northerly route toward Pocatello, Idaho. When US 50 was extended to California it followed the Lincoln Highway's alternate route south of Lake Tahoe.
The last major promotional activity of the LHA took place on September 1, 1928, when at 1:00 p.m. groups of Boy Scouts placed approximately 2,400 concrete markers at sites along the route to officially mark and dedicate it to the memory of Abraham Lincoln. Less commonly known is that 4,000 metal signs for urban areas were also erected then.^[b] The markers were placed on the outer edge of the right of way at major and minor crossroads, and at reassuring intervals along uninterrupted segments. Each concrete post carried the Lincoln Highway insignia and directional arrow, as well as a bronze medallion with Lincoln's bust stating, "This Highway Dedicated to Abraham Lincoln".^[1]
The Lincoln Highway was not yet the imagined "rock highway" from coast to coast when the LHA ceased operating, as there were many segments that had still not been paved. Some parts were because of reroutings, such as a dispute in the early 1920s with Utah officials that forced the LHA to change routes in western Utah and eastern Nevada. Construction was underway on the final unpaved 42-mile (68 km) segment by the 25th anniversary of the Lincoln Highway in 1938.

25th anniversary

On June 8, 1938, President Franklin D. Roosevelt signed the Federal-Aid Highway Act of 1938, which called for a BPR report on the feasibility of a system of transcontinental toll roads. The "Toll Roads and Free Roads" report was the first official step toward creation of the Interstate Highway System in the United States.
The 25th Anniversary of the Lincoln Highway was noted a month later in a July 3, 1938, nationwide radio broadcast on NBC Radio. The program featured interviews with a number of LHA officials, and a message from Carl Fisher read by an announcer in Detroit. Fisher's statement included:

The Lincoln Highway Association has accomplished its primary purpose, that of providing an object lesson to show the possibility in highway transportation and the importance of a unified, safe, and economical system of roads. ... Now I believe the country is at the beginning of another new era in highway building (that will) create a system of roads far beyond the dreams of the Lincoln Highway founders. I hope this anniversary observance makes millions of people realize how vital roads are to our national welfare, to economic programs, and to our national defense ...