According to the invoice from Krumholz, Whitbrooke Harbor is located in Illinois. However, Harbor, on that invoice, is spelled in British or Canadian English (this production being Canadian), i.e. Harbour, and not American English.
According to the Krumholz invoice, the business' postal code is H1C 2C3, locating it in Canada, more specifically Saint-Leonard, a neighborhood in Montreal, QC. However, when Amber goes to the Krumholz office, the George Washington Bridge in New York City is shown.