Delta Air Lines said its passengers can connect to more than 20 cities in China through a partnership that began Wednesday with Chinese carrier China Eastern.

The code-share marketing partnership allows Delta customers to book connections to 21 cities served by China Eastern from its Shanghai hub, including routes to Shenzhen and Nanjing. In turn, China Eastern also puts its "code" on some of Delta's flights.

Delta's routes to China include Detroit-Shanghai and Seattle-Beijing flights, among others, and it will start flying Detroit-Beijing July 1.

Atlanta-based Delta will also relaunch flights from Atlanta to Shanghai on June 5, with two flights a week.