Below is my plan to renumber some roadways, mostly NJ roadways.

First, I would "get rid of" both of NJ's single state US
highways (one through decommissioning, and one through an
extension).

NEW ROAD DESIGNATIONS:

I-76:  Designation extended via NJ-42, Atlantic City Expressway
to Atlantic City.

I-176:  New number for I-676 from I-76 to US-30 in NJ.

I-376:  New number for NJ-55 in NJ.

US-13:  Would remain multiplexed with US-40 (and I-295) up to
and across the Delaware Memorial Bridge.  Would then run along
US-130 to Bridgeport, then along NJ-44 to Delaware Street in 
Thorofare.
	US-13 NORTH would then run via Delaware Street, and CR-631
        meeting up with current US-130 at the 130/295 split.
	US-13 SOUTH would multiplex with I-295 from exits 23 to 22,
        then run along Crown Point Road, meeting up with its
        northbound routing at Delaware Street.
Then, run it along US-130 to it northern terminus at US-1/NJ-171.

US-30:  Would be taken off the expressway in Philadelphia.
From the US-30/I-76 interchange, would continue straight along
Girard Avenue to 6th Street (5th Street westbound) to join
the current routing at the Ben Franklin Bridge.

US-46:  Western extension via bridge into PA, brief multiplex
with PA-611, then the length of current PA-512.

US-46:  Eastern extension to Montauk Point, NY.  See

Kim Russell's ideas for this routing

DE-13:  Much like 202, the state route would cover the routing
of the former US route (thus having a US and DE-13).

PA-13:  Would cover the route of US-13 with the exception of
running along I-76 and US-1 from Girard Avenue to the current
US-1/13 multiplex.

ALTERNATE PLAN:
Historic US-13 signs would be posted along US-13 in PA.

NJ-41:  Would run via Kings Highway from US-130 to join its
current routing in Haddonfield.

NJ-42:  Would run via Black Horse Pike, Mount Ephraim Avenue,
and Haddon Avenue (southbound via Broadway) to the Ben
Franklin Bridge.

NJ-43:  Would run via NJ-47 from Five Points to Brooklawn Circle

NJ-45:  Would multiplex with US-130, then, run along
Broadway up to the Ben Franklin Bridge.

NJ-47:  Would continue straight along the mainline, covering
the NJ-41 routing to Kings Highway in Haddonfield.

NJ-49:  Would continue north along the mainline to I-295.

NJ-141:  New number for NJ-154

CR-551:  Northern terminus would be truncated to NJ-45

(Gloucester) CR-701:  New number for CR-551 between NJ-45 and NJ-47

Alternate PA-13:  Would run along existing US-13 from the I-76
interchange to the current US-1/13 multiplex.

DECOMMISSIONED OR REVISED ROADS:

US-13:
US-40/I-295 to DE/PA line would become DE-13
DE/PA line to I-76 interchange would become PA-13
I-76 interchange to US-1 merge would become Alternate PA-13
US-1 merge to northern terminus would become PA-13

US-130 (decommissioned):
Southern terminus to NJ-44 would become US-13/NJ-49
NJ-44 to I-295 merge would become NJ-49
I-295 multiplex would be stand alone I-295
I-295 split to northern terminus would become US-13

NJ-41:
NJ-41 to Kings Highway would become NJ-47

NJ-42:  Freeway portion would become I-76

NJ-44 (decommissioned):  Would become US-13

NJ-47:  North of Five Points would become NJ-43.

NJ-154:  Would become NJ-141

NJ-168 (decommissioned):  Would become NJ-42

CR-551:
NJ-45 multiplex would become stand alone NJ-45
NJ-45 to NJ-47 would become CR-701
NJ-47 multiplex would become stand alone NJ-43
US-130 (excuse of a) multiplex would become stand alone US-13
US-130 to Ben Franklin Bridge would become NJ-45

Spur CR-551:
US-130 multiplex would become stand alone US-13
US-130 split to northern terminus would become NJ-41

Gloucester CR-631:
NORTHBOUND would become US-13
SOUTHBOUND would be an unnumbered road.

I-676 (PA):
Would run the entire length of the Vine Street Expressway

I-676 (NJ):
Would be renumbered I-176

PA-46:
Renumber it as PA-512.

PA-512:
Renumber it as US-46

Net effect of this, 46 and 512 flip flop numbers in PA.