Robert Peter was born in 1726 in Scotland to Thomas Peter and Jean Dunlop, who were prosperous merchants. He immigrated to the United States around 1745, but there is no definite reason why he chose to leave. He first settled in the town, Bladensburg, along the Anacostia River. In 1751, Georgetown was established, and Robert purchased a lot in the town the following year, and slowly began to build up his land holdings. His land holdings grew to be quite extensive, including owning the entire square from M, K, and 31st Streets, and Wisconsin Ave. From 1789 to 1798, Robert Peter was the first mayor of Georgetown. On December 27, 1767, he married Elizabeth Scott, and together they had 10 children, one of whom died as an infant. Their names were: Thomas, Alexander, Elizabeth, Walter, Robert, Jean, Margaret, David, George, and James. He died in 1806.