sidetrack (n.)

late Old English, "long, broad, spacious; extending lengthwise," from side (n.). Compare Old Norse siðr "long, hanging down." From late 14c. as "being from or toward the side," hence also "subordinate." Also "apart from the main course" of anything, as in side-road (1854); side-trip (1911). In side-eye (by 1922) the notion is "directed sideways."

late 15c., "footprint, mark left by anything," from Old French trac "track of horses, trace" (mid-15c.), possibly from a Germanic source (compare Middle Low German treck, Dutch trek "drawing, pulling;" see trek). Meaning "lines of rails for drawing trains" is from 1805. Meaning "branch of athletics involving a running track" is recorded from 1905. Meaning "single recorded item" is from 1904, originally in reference to phonograph records. Meaning "mark on skin from repeated drug injection" is first attested 1964.

Track record (1955) is a figurative use from racing, "performance history" of an individual car, runner, horse, etc. (1907, but the phrase was more common in sense "fastest speed recorded at a particular track"). To make tracks "move quickly" is American English colloquial first recorded 1835; to cover (one's) tracks in the figurative sense first attested 1898; to keep track of something is attested from 1883. American English wrong side of the tracks "bad part of town" is by 1901. Track lighting attested from 1970.