By Emilie Josephs
Answer: EXCURSION

Each of the provided postcards describe goofy roadside attractions, documented at RoadsideAmerica.com. In the order they are described, here are each of the attractions:

Attraction Location
Cadillac Ranch Amarillo, TX
Oscar Getz Museum of Whiskey History Bardstown, KY
Carhenge Alliance, NE
Evel Kneivel Museum Topeka, KS
Prahbupada’s Palace of Gold New Vrindaban, WV
Cody Dug Up Gun Museum Cody, WY
Dungeons and Dragons Park (Castle Park) Carbondale, IL
Grave of the Confederate Camel Vicksburg, MS
International Church of Cannabis Denver, CO
The Gum Wall Seattle, WA
Beer Can House Houston, TX
Toilet Neptune Guerneville, CA
Cathedral of Junk Austin, TX
Elvis Fight Site Mini-Monument Madison, WI
Trees of Mystery Klamath, CA
Abstract Monument to Fluoridation Grand Rapids, MI
The Mob Museum Las Vegas, NV
Sistine Chapel in Spray Paint Waterloo, IA

Each of Terry’s friends only wrote two postcards. Solvers must group the postcards by author:

Friend Location 1 Location 2
Sammie Trees of Mystery Toilet Neptune
Jack Cody Dug Up Gun Museum The Gum Wall
Ryan The Mob Museum Church of Cannabis
Louise Carhenge Evel Kneivel Museum
Veronica Cathedral of Junk Cadillac Ranch
Susan Beer Can House Grave of the Confederate Camel
Tim Elvis Fight Site Mini-Monument D & D Park
Sarah Sistine Chapel in Spray Paint Oscar Getz Museum of Whiskey History
Gregory Abstract Monument to Fluoridation Prahbupada’s Palace of Gold

For each pair, a line drawn between the two attractions crosses only one letter:

Friend Letter
Sammie E
Jack X
Ryan C
Louise U
Veronica R
Susan S
Tim I
Sarah O
Gregory N

Reading the crossed letters in order from west-to-east yields the answer, EXCURSION.