Here is a list of available names I recently checked:
BinghamCanyonCopperMine.com
BlackCanyonofTheGunnisonNationalMonument.com
CanyonDeChellyNationalMonument.com
CasaGrandeRuinsNationalMonument.com
ChacoCultureNationalHistoricalPark.com
ChimneyRockNationalHistoricSite.com
ColonialWilliamsburgHistoricArea.com
CumberlandGapNationalHistoricalPark.com
FlorissantFossilBedsNationalMonument.com
GlenCanyonNationalRecreationArea.com
GrandStaircaseEscalanteNationalMonument.com
GreatSandDunesNationalParkandPreserve.com
HavasupaiIndianReservation.com
KennedySpaceCenterandCapeCanaveralAirStation.com
LittleBighornBattlefieldNationalMonument.com
MedicineBowMountains.com
MonumentValleyNavajoTribalPark.com
NaPaliCoastStatePark.com
NorthCentralPueblos.com
PecosNationalHistoricalPark.com
PicturedRocksNationalSeashore.com
PuuhonuaoHonaunauNationalHistoricPark.com
SalinasPuebloNationalMonument.com
ScottsBluffNationalMonument.com
SequoiaandKingsCanyonNationalPark.com
SequoiaandKingsCanyonNationalParks.com
SunsetCraterNationalMonument.com
TimpanogosCaveNationalMonument.com
TumacacoriNationalHistoricalPark.com
WaimeaValleyAudubonCenter.com
WatertonGlacierInternationalPeacePark.com
WrangellStEliasNationalPark.com
yes, they are all long, but all are popular historical and tourist locations in US. They are all part of American history and cultural heritage. Many of these were registered before and dropped.
Here is one I just regged: SanBern.com
I rarely register new domains now, but sometimes I stumble upon new list and names I like so I grab them quick.
Not bad domain names listed there