NC 84 was born in 1938 as upgraded routing. It ran from Weddington to Monroe as it does now. Initially, the east end was at US 74/NC 151 at the intersection of Charlotte Av and Franklin (as it ends now).

NC 84 appears 1938 Official

About 1956 or 1957, NC 84 was extended east a couple blocks over what had been part of US 74-A to end at NC 200 which was using Main St at the time.
By 1962, NC 84 was extended along a rerouted NC 200 out Hayne St to US 74-601.

NC 75/84 initial Monroe end 1936 Union County

NC 84 extended to NC 200 1957 Union County

NC 84 extended out to US 74-601 1962 Union County

In December 1978 (NCDOT), NC 84 was truncated back to Franklin/Charlotte intersection in Monroe.
In August 2011 (NCDOT), NC 84 east was truncated back to the newly designated NC 200 along Martin Luther King Jr Blvd west of Monroe. Weddington Rd between NC 200 and Franklin St is now SR 3522.

NC 84 truncated to NC 200 Charlotte St 1982 Union County

NC 84 truncated to NC 200 west of Monroe 2017 Union County