* * * The Central Committee explicitly proposed the third-line construction 1964. 1in may, 965, when listening to the report of the state planning commission on the compilation of the "three five-year plans", * * pointed out: when making plans, we should consider fighting, building third-line bases and doing some first-and second-line military projects. Subsequently, * * * spoke at various meetings many times, and repeatedly emphasized the importance, urgency and necessity of the third-line construction in the instructions and instructions for the "Three Five-Year Plan", which directly led to the decision-making and implementation of the third-line construction in the central government.

The concept of historical geography in the third-tier areas is mainly divided according to the different strategic position of China. Initially, it refers to the southwest and northwest regions "including western Hunan, Hubei and western Henan", and then extended to all or most of the seven provinces and regions west of the Beijing-Guangzhou line, such as Sichuan, Guizhou, Yunnan, Shaanxi, Gansu, Qinghai and Ningxia, as well as western regions such as Henan, Hubei, Hunan and Shanxi.

Large-scale third-line construction lasted more than ten years from the third five-year plan to the end of the fourth five-year plan. From the fifth five-year plan, the third-line construction is mainly supporting construction. Third-line construction mainly adopts three ways: relocation, contracting and new construction. The main goal of the third-line construction is to build the third-line area into a complete industrial system based on "big fight", "early fight" and "nuclear war" with national defense and military industry as the main body, complete categories and self-contained system.

Although the third-line construction, which lasted for more than ten years, objectively changed the unbalanced industrial layout in China and promoted the economic development in the third-line areas, its mistakes and lessons were profound, mainly including:

The biggest mistake in the third-line construction is the misjudgment of the international and domestic situation, which leads to the mistakes in economic construction decision-making. The foothold of the third-line construction is based on international wars, early wars and nuclear wars, thus ignoring the objective conditions of the third-line areas and the proportional relationship between the national economy, and unilaterally emphasizing the development of national defense and heavy industry, resulting in low economic development efficiency.

Secondly, the macro-layout of the third-line construction emphasizes large dispersion, small concentration and self-integration. During this period, the total investment in the third-tier areas reached 200 billion, accounting for most of the national infrastructure investment in the same period, which made the investment center move westward too fast, which was not conducive to playing the role of the old coastal base. On the other hand, it is not conducive to the development of the advantages of the third-tier regions, leading to low investment efficiency, thus delaying the development of the entire national economy; Microscopically, one-sided emphasis on "mountains, scattered caves" ignores the restrictions of geographical location, geographical environment and traffic conditions, which violates the location theory of industrial layout and the objective requirements of socialized mass production, resulting in low efficiency and waste of investment and leaving serious sequelae for the future economic development of third-tier areas.

In short, only by making a correct judgment on the environment can we make scientific economic decisions; Only by acting according to economic laws can the economy develop faster on the basis of high efficiency.