Ever notice, how on the east side of the mighty Willamette, the main and collector numbered streets seem to mostly end in 2?
NE and SE 12th Ave. NE 42nd Ave. SE 52nd Ave. SE and NE 72nd Ave. 82nd Ave. 92nd Ave. 102nd Ave, which feeds into 112th Ave as you go south from Stark St. 122nd Ave. 142nd Ave. 162nd Ave. 182nd Ave. 202nd-not so much so, but there's a light on the part that's a/k/a Gresham's NW Birdsdale Ave and goes between Division and Stark. And there's also 242nd Ave, 272nd Ave and, going east from Gresham, 282nd, and, near Sandy, 362nd.
Going far out into Clackamas country, as the roads thin out so do the presence of numbered avenues, but those that are out there-many of them have 2's. There's a 422nd Ave, and of course, my personal favorite, 502nd Ave.
While I don't have my more arcane maps to hand, I'll bet that, if one looked at them, they'd find that these ending-in-2 avenues land on township lines-which are exactly one mile apart (from 82nd out, 102nd, 122nd, 142nd, 162nd, and 182nd are all one mile (20 standard blocks) apart).
Township lines require a bit of explanation and quite a digression.
Here we go.
When The Great White Father set about to populate the Great American West with colonists, these colonists cared very much about owning this land (this white person still does, what with property taxes being what they are). Land ownership requires records, and records require systems of location.
Thus we came eventually to what's called the Public Lands Survey. At its basis is the idea that you take an large enough (but not too big-then the curvature of the earth messes everything up) and draw perpendicular axes on it (the n-s one is called the meridian, the e-w one is called the baseline) and mark off big squares based on those lines.
These squares are six miles by six miles. This big square has a name too; we call it the township, not necessarily to be confused with the namesake legal and governmental entity found Back East. Each of these logcially divide into 36 1-mile squares, called sections.
Bingo. You now have a neato mosquito way of referencing great tracts of land that, in many cases, you probably haven't even seen yet, dotted here and there with villages of aboriginal people with brown skin who had the unmitigated gall to be there when you went and discovered the places.
Anyway. I told you that stuff to tell you this:
These township, range (the e-w lines are called township lines and the n-s are called range lines) and section lines make very handy boundary and road sites once they are known and cadastrally determined. Farmers used them to delineate ranch and farm lines...and to build roads upon. Thus the repetition of "2-avenues" as you go east; the regularity of the pattern attests to the underlying, ordering structure.
Typically, the 2-avenues are the ones that have been there, in eastern Multnomah county, the longest. The historical name of 122nd Avenue was Buckley Avenue (or Road). I don't know if the others had names,or what they were called when they did.