[osreb]

Myth #3: Americans have always flown the flag
Prior to the Civil War, flags were really only flown in an official capacity on ships, forts and government buildings. “In the antebellum period, if a citizen had flown his flag on his house or carriage, people would have thought that was strange. Why is he doing that? He's not the government,” Ansoff said.
The outbreak of war in 1861 quickly changed Americans’ attitudes about displaying the flag.
"At the beginning of the Civil War there was an outburst of patriotism,” Ansoff said, “and very soon, you saw people flying flags everywhere to show their support for the Union cause