I been collecting old auto signs for 35 years or so & got some 100 years old & up. Sign were made differently in different eras tin signs porcelin neon were all mostly made before the 60s as the mid 60s (shelby era) saw back light plastic signs & posters & cardboard etc signs that werenot made to last forever like porcelin signs are. There are many repo signs made to look old & aged out on the market for sale.