This week's Postal History Sunday is being written "on location" at Chicagopex, an annual event held in (surprise!) Chicago every November. The name "Chicagopex" is a combination of the city name and a shortening of "Philatelic EXposition" or PEX and it is a three-day event where philatelists (stamp collectors) and postal historians gather. There are opportunities to buy and sell items, chances to view interesting exhibits of material, and time to chat with others who have similar or related interests.