The following highways have been numbered 921:
| Preceded by 920 | Lists of highways 921 | Succeeded by 922 |
Wufeng District is a suburban district in southern Taichung, Taiwan. It is the location of Taiwan Provincial Consultative Council.
The Central Cross-Island Highway or Provincial Highway 8 is one of three highway systems that connect the west coast with the east of Taiwan.
Pennsylvania Route 921 is a 10-mile-long (16 km) state highway located in York County, Pennsylvania. The western terminus is at PA 74 in Dover. The eastern terminus is at PA 24 in Mount Wolf. The route is a two-lane undivided road that runs through rural areas and suburban development to the north of York. PA 921 heads northeast from Dover and intersects the southern terminus of PA 297 before it reaches Manchester, where it forms a concurrency with PA 181. From here, the route continues east to its terminus in Mount Wolf. PA 921 was designated in 1928 between PA 24 in Manchester and Mount Wolf. The route was extended west to PA 74 in Dover in the 1940s. PA 24 was extended from east of York to intersect PA 921 at its terminus in Mount Wolf in the 1970s.
King's Highway 109, or Highway 109, is a former provincial highway in Ontario. It was used on two separate, unrelated routes during the 1950s and 1960s:
Secondary Highway 500, commonly referred to as Highway 500, was a secondary highway in the Canadian province of Ontario which was first designated in 1956. Its route was renumbered in 1964, becoming:
Secondary Highway 514, commonly referred to as Highway 514, was a secondary highway in the Canadian province of Ontario. It was used on two separate routes from the 1950s to the 1990s:
