Partnership financing Hughes disliked loans, so he financed the purchase and development of new properties primarily through real estate limited partnerships (RELPs). At first, Public Storage built warehouses and sold them to independent RELPs for a development fee. The company's own RELP, called Public Storage Partners Ltd, was formed in 1975 and closed its first deal for $3 million in investments two years later. Public Storage paid cash to acquire property and build a self-storage facility, then used the property's income to pay investors back and earn a portion as profit. Public Storage Inc. also earned revenues from a portion of each deal that was made. Early investors earned three to four times their money back due to increasing property values in Southern California, high occupancy rates, and increasing storage rental prices. By the mid-1980s, Public Storage was raising $200 to $300 million in investments each year. The RELP format allowed the firm to continue building more locations in the 1970s and 1980s when most of the industry had halted growth because of higher interest rates on loans. In the mid-1980s, co-founder Volk retired and his interest in Public Storage was purchased by Hughes. Forbes estimated that by this time the company was worth $800 million. Investment funding was used to build mini-storage warehouses beyond California, targeting the 39 largest US cities. The firm opened self-storage locations in close proximity to each other, so the sites could share a development office, and justify local television advertising. The firm's growth slowed in the mid-1980s as new competition increased the cost of property and slowed the increase in rental prices to consumers. Poor weather and difficult labor markets outside of California delayed development projects; the company also made poor investments in office parks. Interest in real estate investing also diminished. By the late 1980s, the company opened its 1,000th Public Storage location and the company was three times larger than its nearest competitor in the US market. By 1989, $2.7 billion had been invested from 200,000 investors. Public Storage helped popularize the use of self-storage businesses as a real estate investment vehicle and became one of the longest-running RELP investment vehicles. By 1991, Public Storage had set up more than 150 RELPs and real estate investment trusts (REITs). Real Estate Investment Trust (REIT) According to Financial World, by 1989 the real estate limited partnership (RELP) market that Public Storage relied on for