Best and Worst States at signing concurrencies

[PHLBOS]

Corrections shown below in blue based on later post from Bob7374

Massachusetts is really good.

Almost perfect...they don't sign it when the concurrency is US/MA-x and MA-xA, but the route logs log them as concurrencies.

US 1/MA 1A says hi: https://goo.gl/maps/9KCYy8pcSdPKubzm9

I was about to state similar.  For some reason, this US 1/MA 1A concurrency between Newburyport & Salisbury has been inconsistently signed for decades (signed at the Salisbury end but not the Newburyport end).  I'm not 100% sure if this signed concurrency has always existed.  Part of me wants to say no from the 70s and back.

Another signed MA X/XA concurrency is MA 2/2A between Concord and West Concord.  Such has existed ever since MA 2A was rerouted away from Downtown Concord circa the early 80s.  Prior to the mid-90s/early 2000s(?), there was an old LGS that had the 2A listing (above the CONCORD CENTER legend) greened out at the Elm St. intersection.

[kurumi]

Connecticut is pretty good; I can't think of an overlap signing gap on surface routes, though there may be a few, especially if short.

There are a few gaps on the interstates (which have surprisingly few concurrencies overall... for example, I-91 has about 9 exits involving US 5, but US 5 never hops on board).
* US 6 is mostly ignored when overlapping I-84
* CT 2A is partially signed along the I-395 overlap
* I-95 and US 1 overlap twice, at the Connecticut and Thames rivers, and those are signed pretty well (e.g. on CT 9, 12, 32, 184)

[Rothman]

CT used to infrequently include a small US 6 shield under I-84 trailblazers (some were small and what I'd call "nonstandard").  I remember as a kid wondering how anyone following US 6 would be able to do so.

[bob7374]

Massachusetts is really good.

Almost perfect...they don't sign it when the concurrency is US/MA-x and MA-xA, but the route logs log them as concurrencies.

US 1/MA 1A says hi: https://goo.gl/maps/9KCYy8pcSdPKubzm9

I was about to state similar.  For some reason, this US 1/MA 1A concurrency between Newburyport & Salisbury has been signed for decades.  I'm not 100% sure if this signed concurrency has always existed.  Part of me wants to say no from the 70s and back.

Another signed MA X/XA concurrency is MA 2/2A between Concord and West Concord.  Such has existed ever since MA 2A was rerouted away from Downtown Concord circa the early 80s.  Prior to the mid-90s/early 2000s(?), there was an old LGS that had the 2A listing (above the CONCORD CENTER legend) greened out at the Elm St. intersection.

IIRC from the Newburyport Road meet, the sign in the link above was the last including both US 1 and 1A heading south, there were no signs of the concurrency once crossing into Newburyport. Before that, you have this sign at the start of the bridge over the Merrimack River: https://goo.gl/maps/qZiDtVDFhjpnCJjG7