SAN FRANCISCO, May 22 (Xinhua) -- The governor of the U.S. state of Washington said Friday that decisions of reopening states should be driven by data and science, not the calendar, as more counties started reopening.

"We are making good progress as we continue to open Washington in segments. Currently, one-third of our state is now eligible to move into Phase 2. We are hard at work to determine next steps as we move closer to the May 31 expiration of my current order," said Jay Inslee in a statement.

The statement was made after the Washington State Department of Health announced that an additional four counties are eligible to move to Phase 2, a higher level of reopening under the four-phased Safe Start plan.

The Safe Start plan sets a data-driven approach to emerge from the pandemic, modifying business closures and physical distancing measures while minimizing the health impacts of COVID-19.

"As I have repeatedly said before, these are decisions that are driven by public health data and science, not the calendar," Inslee said.

"This does not mean that we will be able to open every county in the state on June 1. Counties that continue to have large numbers of infections are not in a position to open up stores, restaurants and services safely," he added.

Washington state began the phased process of gradually reopening its communities and economy on May 4.

According to the plan, readiness must be achieved in four areas to proceed from each phase: healthcare system readiness, testing capacity and availability, case and contact investigations, and ability to protect high-risk populations.

Inslee also urged people to continue to physically distance, spend time with family, and stay close to their residences during this year's Memorial Day weekend.

The Memorial Day weekend is traditionally a time for Americans to get outside, travel to their favorite vacation destinations, and welcome the return of summer.