Are national parks constitutional?

[MODU]

I would have to say yes.  Most of the lands which are now national parks were not owned by private individuals at the time they became parks.  And while states are the care-takers of the land, the states are a part of the government, and the government has the right to decide the purpose of unused land within the country.

[MODU]

State governments are wholly independent of the federal govt.

That's not techically correct.  While states do possess the right to manage themselves, they do answer to the higher authority.  The Confederate states thought they were independent and were proven wrong.  That is why we are the "United" states, not the "50 Loosely alligned" states.  Fortunately, our government is structured to allow balance between state rights and the will of the federal government, so there isn't an overt abuse by either party in this marriage.

[MODU]

  The Confederate states thought they were independent and were proven wrong. 

Actually they were a sovereign independent nation was was invaded and forced to comply by force of bayonet.

hahaha . . . so even then, they were not independent states, but rather shared authority with a higher power.

[MODU]

I would agree with him: I think that educating people and maintaining the interstate highways is more important than maintaining a park.

But we can have all three, and, we can have them together.  National Parks serve as great educational centers.  Additionally, you have many highways and parkways through National parks which provide for a touch of nature from the comforts of your car, while at the same time, preserving the nature around the road.  I don't think we need to make these concepts mutually exclusive.