Grant set up a law practice, then gave it up to invest in real estate. He purchased property throughout San Diego. In 1895, he bought the Horton House hotel. He wanted to run the hotel and name it after his father. In 1905, he razed the old hotel and built a new one, the U.S. Grant Hotel, in 1910. San Diego voters helped finance $700,000 for the $1.5 million needed to construct the hotel after Grant lacked the funds to do so. During his time in San Diego, Grant became a close associate of Charles T. Hinde, E.S. Babcock, and John D. Spreckels. Hinde and Grant served on the boards of directors of multiple banks and invested in many companies and business ventures together.