If you decided you wanted some minor modification such as, say, a bay window, there were smaller kits which would be shipped by parcel post.
The post office was a logistical marvel in those days. You could post a letter in Maine and it would typically arrive at a destination in California three days later, maybe four if it was too far off a main rail line. Trains plied the tracks 24/7 and ran on time. Many of these trains included a postal rail car which had a crew sorting mail en route. Bags were coded according to station and direction and could be picked up and dropped off with a special hook and pulley arrangement even if the train didn't make a stop at that particular station.
Sorting errors were rare and were usually caught by the destination station master and rerouted before the postal patron even noticed a delay in delivery.
The rest is history.
Ahh, yes the glory of the days of Outcome-Based performance management. Now workers expect a trophy just for showing up on time and everyone, especially the employer, must defer to each employee’s ‘identity’.
My uncle Jack was in charge of a mail crew that sorted mail on the train. I always thought he worked for the post office but when my aunt passed away I helped go through her things and the retirement he got was from the railroad not the postal service.
Yes the mail was far more efficient than it is now.
I remember my dad riding the trains as postal clerk. He carried a pistol. I thought that was cool.
Then he spent a few years sorting mail in a bus-like truck. It was akin to the rail cars, but on a bus platform.