<b>A dataset of inter-county distances along the real-world highway and railway networks in the contiguous United States</b>

Because the highway and railway network graphs are undirected, the reported inter-county distances are symmetric, although both origin–destination directions are retained as separate records.</p><p dir="ltr">In the construction procedure, the <i>adjusted geometric centroid</i> of each county is used as the spatial reference for representative-node selection. Only network nodes assigned to the same county GEOID and belonging to the <b>largest connected component</b> of the corresponding transportation network are retained as <i>qualifying network nodes</i>.

The qualifying node nearest to the adjusted geometric centroid is selected as the <b>representative network node</b> for that county. The adjusted geometric centroid itself is not used directly as an origin or destination in the shortest-path calculation. Instead, inter-county shortest-path distances are computed between the selected representative network nodes using edge-length weights along the corresponding real-world highway or railway network.</p><p dir="ltr">Each record contains the origin county GEOID (<i>ori_geoid</i>), origin county and state name (<i>ori_name</i>), origin adjusted geometric centroid latitude and longitude (<i>ori_centroid_lat</i>, <i>ori_centroid_lon</i>), origin mode-specific representative network-node latitude and longitude (<i>ori_node_lat</i>, <i>ori_node_lon</i>), destination county GEOID (<i>des_geoid</i>), destination county and state name (<i>des_name</i>), destination adjusted geometric centroid latitude and longitude (<i>des_centroid_lat</i>, <i>des_centroid_lon</i>), destination mode-specific representative network-node latitude and longitude (<i>des_node_lat</i>, <i>des_node_lon</i>), transportation mode (<i>mode</i>), and inter-county shortest-path distance in miles (<i>distance</i>).

All latitude and longitude coordinates are reported in <b>WGS 84 (EPSG:4326)</b>.</p><p dir="ltr">The highway network is constructed from highway features classified as <b>Classes 1–2–3</b>, corresponding to freeways, primary highways, and secondary highways or municipal arterials, respectively. The railway network is constructed from railway features categorized as <b>M, I, or O</b>, corresponding to the main sub-network, major industrial leads, and other tracks (minor industrial leads), respectively.

The transportation infrastructure data are obtained from datasets maintained by the U.S. Department of Transportation Bureau of Transportation Statistics.</p><p dir="ltr">The dataset can support applications in <b>transportation planning, infrastructure investment, freight transportation, and supply chain and logistics analysis</b>. The accompanying reproducibility code is available separately as a Figshare Software item at DOI: <b>10.6084/m9.figshare.33936526</b>.</p>