The Texas Demographic Center projects Hidalgo County will have about 948,000 residents by 2020 — falling slightly short of the million mark.

Whether or not Hidalgo County will have 1 million residents by 2020 depends on the most difficult part of projecting population changes: migration.

If the net migration Hidalgo County experienced from 2000 to 2010 remains unchanged through 2020, the county will reach 1 million. If net migration slows, though, Hidalgo County will fall short.

State Demographer Lloyd B. Potter said experts project population growth in Hidalgo County will follow what the state Demographic Center calls the “0.5 Scenario” — slowing by half.

Regardless, the Rio Grande Valley remains among the fastest growing parts of the country.

“It grows approximately 20 percent per decade, which is quite impressive for the United States,” said Igor Ryabov, a sociology professor at the University of Texas Rio Grande Valley.

Correctly counting the number of Hidalgo County residents remains a tricky task.

After the 2010 U.S. Census, the county formally challenged the population count.

Census workers may undercount rural residents. People who aren’t legally present in the United States — or who simply don’t trust the federal government — may not cooperate with the census. Both problems remain common on the border.

Correctly counting the number of residents carries big implications for federal funding.

“Whether it’s infrastructure whether it’s public health — whether it’s anything — we need a fair count so that we can help our people,” said Hidalgo County Precinct 4 Commissioner Joseph Palacios.

Correction: State Demographer Lloyd B. Potter said he expects Hidalgo County’s population growth to follow the 0.5 Scenario, meaning the county’s population will fall slightly short of 1 million people by 2020.