During the 1970s, Denver served as the airline's main hub. The 747s were focused on the Chicago-Los Angeles-Honolulu routes, with one daily round trip through Denver. The DC-10s served large markets (Los Angeles to Chicago, Denver, Houston and Honolulu; and from Denver to Chicago, Los Angeles, Seattle and Houston). DC-9s and 727s predominated elsewhere and added frequencies on DC-10 routes. Next to Braniff, Continental operated fewer aircraft types (four: the 747, DC-10, 727-200, and DC-9-10) during this period than any U.S. trunkline, affording savings in parts, maintenance, and crew training. The DC-10 enabled the airline to capitalize on traffic growth in the west. Continental saw market share grow annually in each DC-10 market through the 1970s, until relative market parity was achieved with United, the principal competitor on most of the DC-10 routes. The same innovations introduced on the 747s appeared on Continental's DC-10s, including the "Polynesian Pub", but after the 1973 oil crisis more seats were needed and the DC-10 pubs were removed. Continental phased out its 747s in 1978 in favor of the DC-10s (747s would return to Continental during the Lorenzo era, flying Newark to London and Paris). From the mid 1970s until it merged with Texas International, Continental operated only DC-10s, 727-100s, and 727-200s.