Carrie's personal aspirations to better herself lead her to spend part of her scanty funds on an umbrella. This situationally ironic choice, influenced by vanity, results in a rift with her financially conscious sister, Minnie. It also foreshadows Carrie’s later troubles:
On the first morning it rained [Carrie] found that she had no umbrella. Minnie loaned her one of hers, which was worn and faded. There was the kind of vanity in Carrie that troubled at this. She went to one of the great department stores and bought herself one, using a dollar and a quarter of her small store to pay for it.
"What did you do that for, Carrie?" asked Minnie, when she saw it.
"Oh, I need one," said Carrie.
"You foolish girl."
Carrie resented this, though she did not reply. She was not going to be a common shop-girl, she thought; they need not think it, either.
The irony here is multifaceted. Carrie wants to buy an umbrella because the one that’s being offered to her will make her look poor. However, she’s too poor to afford an umbrella without risking her financial future. Carrie's actions, driven by a need to appear as if she has disposable income, ironically bind her closer to a reality she is striving to avoid. Purchasing the umbrella isn't merely about protection from rain; it's symbolic of her desire to shield herself from the judgments of society. If she has a nice new umbrella, she believes people won’t think she is “common.”
Furthermore, the incident provides foreshadowing; readers see early signs of Carrie's inclination towards luxury, even when it’s impractical or actually risky. This rash choice hints at future ones like it, informed by a mix of vanity and ambition.
