**2. Literature Review**

#### *2.1. Linear Cultural Heritage*

Concepts similar to LCH include the ideas of "cultural route" and "heritage corridor". However, these three concepts originate from different social backgrounds and have strong time and place characteristics [6]. The cultural route mainly originates from European countries, and this concept is accompanied by the political and cultural demands required for developing European integration. As the world's first cultural route heritage selected for the "World Heritage List", the routes of Santiago de Compostela are regarded by the European Commission as a carrier for carrying collective memory, as well as crossing borders and language barriers, to seek cultural identity for different countries and nationalities in Europe [17]. After more than 30 years of development, related research has gradually been enriched, focusing on the classification of cultural routes, such as railways [18], canals [19], and pilgrimage routes [20], as well as tourism-related research, such as economic promotion [21], ecological protection [22], and sustainable development [23,24].

The heritage corridor is rooted in the vast natural environment of the United States. It has neither political demands for "identity" at the national or international level nor the meaning of "national symbol". It manifests itself as "a linear landscape with a collection of special cultural resources" [25]. The heritage corridor emphasizes the overall understanding of the historical and cultural value of the corridor, uses heritage to achieve economic revival, and solves problems, such as landscape similarities, the disappearance of community identity, and economic recession [6]. This shows that the core goal of the heritage corridor is to help the economic development of the areas that classify as linear through heritage protection. This approach's spillover effect beautifies the natural environment, enriches the cultural landscape, and forms a community identity. By protecting cultural elements along the heritage corridor, the linear space, not originally known as "heritage", has become increasingly cultural. Overall, compared with the cultural route, the heritage corridor has more grassroots characteristics. It is used as a strategy or planning method for local development rather than starting from heritage protection, such as cultural routes, as an objective type of heritage.

Judging from the research, the cultural route and heritage corridor are important theoretical references for the study of LCH in China. Due to the spatial distribution and the quantitative advantages of heritage types, most scholars believe that LCH belongs to cultural heritage agglomeration [10,25]. The morphological characteristic of LCH is another crucial point emphasized, and it is always expressed in terms of "belt", "edge", "strip", and "corridor" [6]. In terms of vocabulary composition, LCH is a cross-cutting concept composed of three words: "linear" refers to the extension of space; "culture" is its essential attribute; "heritage" corresponds to the value identity of modern society. It suggests that LCH is a vital link formed for the specific purpose of humanity. It connects some originally unrelated towns or villages to form a chain-like state of cultural heritage [25]. The connotation of LCH can be explained by subject, completeness, and authenticity. The cultural background of the linear space reflects the subject [6,26,27], while the geographical characteristic reflects completeness [22,28] and authenticity is the fundamental attribute of cultural heritage [29,30].
