NC 170 #1 appeared in 1929 as a renumbering of NC 512, running from US 15/NC 75 (now NC 73) near Norman north to US 311/NC 70 (now NC 211) Candor.
In 1932, US 411 was added to the entirety of NC 170.
In late 1934, US 411/NC 170 was renumbered as US 220. Today it is US 220 ALT.
This NC 170 was a numbering violation, being a x70 route instead of a 70x or 75x route.

NC 512 south of Candor 1928 Gen Draft

NC 512 becomes NC 170 1929 Blue Book

NC 170 #2: Appeared in 1935 as new primary routing, running from US 17 Elizabeth City south to Weeksville.
In 1940, NC 170 was extended northeast with NC 30 to Belcross, then replaced NC 30 to Sligo, then replaced NC 34 to the Virginia line.
In 1958, NC 170 was renumbered as NC 168. Sligo to Belcross is now NC 34; Belcross to Elizabeth City is US 158; Elizabeth City south to Halstead Blvd is unnumbered Herrington Rd; south to Weeksville is NC 344.

NC 170 #2 appears 1935 Official

NC 170 in 1955 1955 Official

NC 168 replaces NC 170 1963 Official