National_Parks

park_idnamelocation
1YellowstoneWyoming
2Grand CanyonArizona
3Rocky MountainColorado
4EvergladesFlorida
5Great Smoky MountainsTennessee

Trails

trail_iddifficultylength
1Beginner_Trail1.0
2Moderate_Trail3.0
3Difficult_Trail6.0
4Expert_Trail9.0
5Family_Friendly_Trail2.0

National_Parks_Trails

national_park_idtrail_id
(→ National_Parks.park_id)(→ Trails.trail_id)
11
21
31
41
51
52