How it started
Background
Donald Trump's grandparents Frederick Trump and Elizabeth Christ Trump were a German immigrant couple who moved to the borough of Queens in 1907. Frederick began developing real estate there. He died during the "Spanish flu" pandemic in 1918, leaving an estate valued at $31,359 (or about $535,381 in 2020).
Elizabeth carried on in the real estate business after her husband's death. She had contractors build houses on the empty lots Frederick had owned, sold the houses, and earned income off the mortgages she provided to buyers.
Her middle child, Donald Trump's father Fred Trump, entered the carpentry trade after graduating high school in 1923. Fred would later say he completed his first single-family home in 1924, but other sources date his start as a builder to 1927. In that year, Fred reached the age of majority, and "E. Trump & Son", a name Elizabeth had used in ads since 1921, was formally incorporated.
In 1929, with Fred at the helm, the company began developing pricier houses in nearby Jamaica Estates. In the deepening depression, the company went out of business. In 1933 Fred opened a supermarket, called "Trump Market", then quickly sold it and returned to the real estate business. Around this same time, Fred Trump and a partner acquired the mortgage-servicing subsidiary of Brooklyn's J. Lehrenkrauss & Co., which had gone bankrupt and subsequently been broken up amid charges of fraud. This gave Trump access to the titles of many properties nearing foreclosure, which he bought at low cost and sold for a profit. He quickly became known as one of New York City's most successful young businessmen. In 1935, the company moved to Brooklyn, where, in addition to Queens, Trump was a prolific builder of single-family homes.
During World War II, Trump constructed apartments and temporary housing for military personnel in Virginia and Pennsylvania. In 1944, he shifted his focus back to Brooklyn and began planning to develop large apartment buildings. He opened the 1,344-unit Shore Haven complex in 1949, followed by Beach Haven in 1950 and Trump Village in 1964.
From Wikipedia’s article on The Trump Organization, shared under CC BY-SA 4.0.2