The 2019 North American hard court swing kicks off next week as the tour begins the US Open Series on opposite coasts in California and Washinton D.C., before meeting in the middle in Toronto and Cincinnati and heading east to the final Slam of the season at the US Open, which begins on August 26th. 

A look back at who dominated the summer hardcourts last season:

Mubadala Silicon Valley Classic (San Jose, California)
2018 Final: Mihaela Buzarnescu d. Maria Sakkari, 6-1, 6-0.

Citi Open (Washington D.C.)
2018 Final: Svetlana Kuznetsova d. Donna Vekic, 4–6, 7–6(7), 6–2.

Rogers Cup (Toronto, Canada)
2018 Final: Simona Halep d. Sloane Stephens, 7–6(6), 3–6, 6–4.

Western & Southern Open (Cincinnati, Ohio)
2018 Final: Kiki Bertens d. Simona Halep, 2–6, 7–6(6), 6–2.

US Open (New York, New York)
2018 Final: Naomi Osaka d. Serena Williams, 6-2, 6-4.

This year also sees the addition of the NYJTL Bronx Open, an international event that will take place the week before the US Open. 

Here's where the Top 20 are currently entered:

Non Top 20 Notes:

- Victoria Azarenka, Donna Vekic, Amanda Anisimova, Maria Sakkari, Andrea Petkovic, and Jelena Ostapenko are also entered in San Jose. Garbińe Muguruza has withdrawn.

- CoCo Vandeweghe is set to make her return to singles competition in San Jose after being awarded a main draw wildcard. Vandeweghe has not played a singles event since 2018 Beijing due to foot injury. Also taking wildcards into San Jose are Daria Kasatkina and Bethanie Mattek-Sands. 

- Hsieh Su-Wei, Sofia Kenin, Kristina Mladenovic, Monica Puig, Iga Swiatek, and Eugenie Bouchard are also entered in Washinton D.C. Bianca Andreescu has withdrawn.

- Victoria Azarenka and Venus Williams are currently main draw alternates for Toronto. 

- Using her Special Ranking at No.43, CiCi Bellis is currently entered in the main draw in Cincinnati. The 20-year-old American has not played a match since 2018 Miami due to arm injury

- The inaugural event in the Bronx has a strong field shaping up, with Anett Kontaveit, Dayana Yastremska, Maria Sakkari, Aliaksandra Sasnovich, Ajla Tomljanovic, Yulia Putintseva, Alize Cornet, and Barbora Strycova entered.