Why does I-70 not go to Philadelphia?

[tidecat]

Does anyone know the history behind why Philadelphia wound up with I-80S and eventually I-76, and why I-70 cuts down from Pennsylvania to go to Baltimore?  I know today's I-68 didn't come along until 1991, and the designation was originally meant for what is now I-595, but it seems like it would make more sense for I-70 to go to Philadelphia.  Even in the suffixed era, Philadelphia could have been I-70N and Baltimore could have been I-70S.

[TXtoNJ]

Does anyone know the history behind why Philadelphia wound up with I-80S and eventually I-76, and why I-70 cuts down from Pennsylvania to go to Baltimore?  I know today's I-68 didn't come along until 1991, and the designation was originally meant for what is now I-595, but it seems like it would make more sense for I-70 to go to Philadelphia.  Even in the suffixed era, Philadelphia could have been I-70N and Baltimore could have been I-70S.

I-70S originally was supposed to go to DC.

[SteveG1988]

Does anyone know the history behind why Philadelphia wound up with I-80S and eventually I-76, and why I-70 cuts down from Pennsylvania to go to Baltimore?  I know today's I-68 didn't come along until 1991, and the designation was originally meant for what is now I-595, but it seems like it would make more sense for I-70 to go to Philadelphia.  Even in the suffixed era, Philadelphia could have been I-70N and Baltimore could have been I-70S.

I-70S originally was supposed to go to DC.

Odds are the reason why Baltimore got I70 was due to Annapolis. Since many interstates were designed for use in a national defense system. Also odds are it was deemed adequate to have one non suffixed 2di per city, and Philly was set for 95, and 80S/76. Also wasn't 70 a second round interstate to begin with, after philly was given 80s?

[triplemultiplex]

Also wasn't 70 a second round interstate to begin with, after philly was given 80s?

There's your answer.  76 was originally 80S so of course it made sense to send 70 toward Bal-Wash.  Then they decided against making more split interstates and by then it's 'too late'.

[thenetwork]

And that I-76 was the perfect interstate number for Philadelphia (1776)   

[NE2]

[kphoger]

^^ Rock your interstate, Florence Kansas!

[OCGuy81]

Cool map, NE2.  Interesting seeing I-31 running from Fargo to the Canadian border, along with the I-82 designation for what's now I-84 today.

[roadman65]

Hey I am amazed that Jake from San Diego did not respond to this one in the first post something like " Because it goes to Baltimore."

Anyway, the bigger question is why did I-70 go to the PA Turnpike and not stay south of the PA Border in WV and MD?  That would have taken care of the Breezewood situation.

[renegade]

Hey I am amazed that Jake from San Diego did not respond to this one in the first post something like " Because it goes to Baltimore."

Beat me to it.  I was going to say, "Because it goes to Wheeling." 

[bzakharin]

For that matter, why does US-40 have the odd routing it does today beyond Baltimore? Was there a reason at the time to connect Baltimore with Atlantic City (seeing as US-30 already provide a more northerly routing that was later more or less duplicated by I-76/NJ-42/Atlantic City Expressway)  that didn't exist later when the Interstate system was built?

[NE2]

For that matter, why does US-40 have the odd routing it does today beyond Baltimore?

What's odd about it?

[briantroutman]

Another way to look at it: I-70 is essentially the Interstate replacement for US 40–which in turn was predated by the National Road (among other named roads) and was also roughly the corridor served by the Baltimore and Ohio railroad. All of these routes connected the Baltimore/Washington area with Ohio and the Midwest, so it makes sense that I-70 would follow.

You're looking at a map, following I-70 from west to east, and when you get to Breezewood, you ask "why does I-70 jog sharply south here?" . You should be doing the opposite–following I-70 from east to west and ask "why does I-70 turn north at Hancock?" .

For BPR planners in the 1950s, routing I-70 over the already completed Pennsylvania Turnpike through the Appalachian ridges and Laurel Highlands was a way to bring the Interstate System closer to completion while reducing the amount of new construction required and circumventing some of the engineering challenges posed by the terrain. I wouldn't doubt that representatives of the PTC and PDH campaigned for this routing as well.

In another thread, I speculated on how the routing of I-80 would be different had the Pennsylvania Turnpike never been constructed. I think the question is just as valid here–I-70 likely would have followed the present routing of I-68 at least through Cumberland before angling northwestward through Washington (Pa) and Wheeling.

Considering the number of Interstates that closely followed their US Route predecessors, the Pennsylvania Turnpike is kind of a historical aberration that drastically altered the destinies of at least a few Interstate designations.

[SteveG1988]

Another way to look at it: I-70 is essentially the Interstate replacement for US 40–which in turn was predated by the National Road (among other named roads) and was also roughly the corridor served by the Baltimore and Ohio railroad. All of these routes connected the Baltimore/Washington area with Ohio and the Midwest, so it makes sense that I-70 would follow.

You're looking at a map, following I-70 from west to east, and when you get to Breezewood, you ask "why does I-70 jog sharply south here?" . You should be doing the opposite–following I-70 from east to west and ask "why does I-70 turn north at Hancock?" .

For BPR planners in the 1950s, routing I-70 over the already completed Pennsylvania Turnpike through the Appalachian ridges and Laurel Highlands was a way to bring the Interstate System closer to completion while reducing the amount of new construction required and circumventing some of the engineering challenges posed by the terrain. I wouldn't doubt that representatives of the PTC and PDH campaigned for this routing as well.

In another thread, I speculated on how the routing of I-80 would be different had the Pennsylvania Turnpike never been constructed. I think the question is just as valid here–I-70 likely would have followed the present routing of I-68 at least through Cumberland before angling northwestward through Washington (Pa) and Wheeling.

Considering the number of Interstates that closely followed their US Route predecessors, the Pennsylvania Turnpike is kind of a historical aberration that drastically altered the destinies of at least a few Interstate designations.

To put it simply, i70 jogs into PA the way it does due to it being cheap to just route it along an existing route. Same reason 40 was built the way it is between baltimore and points west, it follows exiting routes. PA probably saw it as a way to use interstate funding elsewhere since that would be money saved due to routing it over the exiting turnpike.

[roadman65]

Never thought about I-70 and I-80 being built where they are now because the PA Turnpike pr-existed before it.  Even though I knew the PA Turnpike was there from 1940 and then extended in sections later, its a good point how if it was not there where I-80 would have been or I-70's alignment as well.  That is what is amazing.

Glad you brought it up.  It does answer questions of why the N-S jog from Hancock to Breezewood.  That, I feel, is the root behind why the OP originally wanted to know why Baltimore?  It should be like Brian said, to ask why it does not continue N-W from Hancock and not why does it go S-E from Breezewood.

[bugo]

For that matter, why does US-40 have the odd routing it does today beyond Baltimore?

What's odd about it?

I always thought it was even.

[TEG24601]

I prefer the answer - Nobody thought it through.  Had anyone been really paying attention when they were thinking about the numbering, they would have started by numbering up the West Coast and East Coast, then connecting the two numbers together, by the best route possible.  We still would have had I-90 from Seattle to Boston, but I suspect I-10 would have been San Diego to Jacksonville, I-20 from LA to Charleston, I-30 from LA to Charlotte/Fayetteville, I-40 from San José to Norfolk, I-50 from San Francisco to Washington, I-60 from Sacramento to Atlantic City, I-70 Eugene or Boise to Philadelphia, and I-80 from Portland to New York.  Instead, they simply threw down lines, using roads that were already built, and added numbers later, not to mention the rules about states having two routes with the same number, which, when you are using shields, and they are also called different names, doesn't make any sense.

[roadman65]

Also to keep in mind that not only was the US route system created by existing state highways, but they chose the alignments to serve major cities too.  That is why US 1 deviates from I-95 between Petersburg, VA and Jacksonville, FL.

It was that both VA, NC, and SC wanted the road to transit their state capitals. Also they wanted it to serve DC as well which is why it does not go the route of US 13 and US 17 between Philadelphia and Jacksonville. 

Later when the interstates came along they wanted them to follow some of the US routes that were already in place.  However, some would allow for their former US routes to serve some cities by itself so the states in some places had the interstate bypass that small city especially if that particular place would take the interstate in a not so straight line.

It is all about what was before that created what is now.

[NE2]

I prefer the answer - Nobody thought it through.

This post is a perfect example of the Dunning-Kruger effect.

[Henry]

I think it was for the best that I-70 never went anywhere near Philly. I-76 is a more fitting number for that city, and to have I-70 serve the Baltimore/Washington megalopolis was a good compromise.

[bzakharin]

For that matter, why does US-40 have the odd routing it does today beyond Baltimore?

What's odd about it?

I guess looking at a map it's not that out of place cardinal direction-wise. It just feels wrong because of the shape of the east coast. Still, as mentioned before, I-70 is essentially a replacement for US-40, so I'd expect US-40 to terminate in Baltimore or I-70 to go on to Atlantic City. Instead, US-40 parallels I-95, a North-South route through eastern Maryland and Delaware, and there is no Interstate equivalent to US-40 in NJ.

It certainly feels like they went out of the way to connect Atlantic City to the US highway system from 5 directions (US-30, US-40, US-322, and indirectly US-9 mean it has links to Philadelphia, Baltimore, Harrisburg, New York, and Salisbury). On the other hand, it has zero interstates and two freeways, so it is connected only to Philadelphia and New York.

[roadman65]

Remember you are talking about New Jersey.  I lived there all of my life up until age 25, and they were not that anxious to expand the given interstate mileage even though most was lost due to the cancelled Union County Expressway (I-278) and Somerset Freeway (I-95).

We have talked about it so much here of making the ACE part of I-76 many times it has gotten old already.  Yes, it is odd, but no New Jersey does not seem interested in adding more interstates and most of us New Jerseyans consider the Parkway and ACE as interstates even though they are not.

[cpzilliacus]

Does anyone know the history behind why Philadelphia wound up with I-80S and eventually I-76, and why I-70 cuts down from Pennsylvania to go to Baltimore?  I know today's I-68 didn't come along until 1991, and the designation was originally meant for what is now I-595, but it seems like it would make more sense for I-70 to go to Philadelphia.  Even in the suffixed era, Philadelphia could have been I-70N and Baltimore could have been I-70S.

I-70S originally was supposed to go to DC.

It made it as far as the Pooks Hill interchange on I-495 (Exit 34 today) in the Bethesda area of unincorporated Montgomery County, Maryland, about 4 miles north of the D.C. border

In about 1973  or 1974, I-70S became I-270.

[cpzilliacus]

We have talked about it so much here of making the ACE part of I-76 many times it has gotten old already.  Yes, it is odd, but no New Jersey does not seem interested in adding more interstates and most of us New Jerseyans consider the Parkway and ACE as interstates even though they are not.

Having driven all of the ACE as recently as January 2015, I believe it would require a fair amount of upgrading in order to be awarded an Interstate number.  For starters, several of the overpasses are not Interstate-standard height.

[roadman65]

We have talked about it so much here of making the ACE part of I-76 many times it has gotten old already.  Yes, it is odd, but no New Jersey does not seem interested in adding more interstates and most of us New Jerseyans consider the Parkway and ACE as interstates even though they are not.

Having driven all of the ACE as recently as January 2015, I believe it would require a fair amount of upgrading in order to be awarded an Interstate number.  For starters, several of the overpasses are not Interstate-standard height.

That and NJ 42 has a lot of substandard issues as well. 

NJDOT wrote me back once saying that your reason above is that it would require a lot of work to get it done to be interstate quality. 

That is another reason to add to the list.  However, I do not see why this would be a problem since I-70 from New Stanton to Washington, PA is not to standards, I-78 from Hamburg to Fogelsville in PA is certainly not, and NJ 495 was allowed for years to be interstate and that we know is far from it.