Since we now have a thread about four lane roads that are too wide, I figured I might as well revive my thread about the reverse, just to remind everyone that it exists

I decided to compile a list for this thread using
NYS Traffic Data Viewer as a guide. Any state and US highways in
orange (volumes over 10K) could be included in a potential widening program, in addition to several other corridors with high volumes of trucks and long distance traffic. Below is a list by county, starting in Western New York and working east. I excluded county routes and local streets, since they are generally handled by the local jurisdiction and not the state.
Niagara CountyNY 31 from I-190 to Middleport
Erie CountyUS 62 from Hamburg to Eden
NY 16 from NY 400 to Yorkshire
NY 78 from French Rd to NY 263
NY 425 from North Tonawanda to NY 31
NY 5 from Harris Hill to Akron
Cattaraugus CountyNY 417 from Olean to Portville
Steuben CountyNY 36 from I-390 to I-86
Chemung CountyNY 14 from Watkins Glen to Elmira
Livingston CountyUS 20A from Geneseo to Livonia
US 20/NY 5 from Avon to Lima
Monroe CountyNY 104 from NY 19 to NY 386
NY 404 from Gravel Rd to NY 250
NY 286 from Qualtrough Rd to NY 250
NY 441 from Watson Rd to County Line
NY 65 from NY 31 to Calkins Rd
NY 31 from French Rd to I-490
NY 31 from Turk Hill Rd to Wayne County Line
NY 250 (entire length)
Ontario CountyUS 20/NY 5 from Canandaigua to Geneva
NY 96 from I-490 to NY 332
Wayne CountyNY 104 from Williamson to Wolcott
NY 31 from Monroe County Line to Lyons
Seneca CountyUS 20/NY 5 from Geneva to Waterloo
Cayuga CountyUS 20/NY 5 from NY 318 to Auburn
US 20 from Auburn to Skaneateles
NY 5 from Auburn to Onandaga County Line
Oswego CountyNY 481 from Fulton to Oswego
Onandaga CountyNY 5 from Cayuga County Line to Camillus
NY 31 from Baldwinsville to Cicero (whatever isn't already)
NY 92 from NY 5 to Cazenovia
NY 5 from Fayetteville to Madison County Line
NY 173 (entire length)
Madison CountyNY 5 from Onandaga County Line to Vernon
Jefferson CountyUS 11 from I-781 to St Lawrence County Line
St Lawrence CountyUS 11 from Jefferson County Line to Potsdam
Saratoga CountyNY 67 from Amsterdam to Ballston Spa
NY 50 from Scotia to Saratoga Springs
Corridors To Be Considered For A Full FreewayUS 20A from East Aurora to I-390
US 219 from Springville to Salamanca
NY 31 from Adams Basin to Orleans County Line
NY 13 from Ithaca to Cortland
As you can see, a four-laning program is definitely in order!