Los Angeles County had 98,608 more people leave than move in last year, the largest net outmigration among the nation’s big counties.

That’s a highlight of what I learned when I filled my trusty spreadsheet with fresh U.S. Census Bureau population data for the 176 largest counties with 400,000 residents or more as of July 1, 2018. Domestic net movement comprises moves to or from elsewhere in California or the nation.

Taking into account Los Angeles County’s 10.11 million population — the biggest in the nation — outflow was equal to 0.98% of all residents, 20th worst among the 176 counties. Historically speaking, last year’s outmigration was up compared with an average 57,136 outflow from 2010 to 2017.

A “the-more-the-merrier” perspective isn’t always true for the population.

Note that many locals think the region’s already too crowded. They may cheer slow-growth numbers as it’s a trend that might help ease congestion — both in neighborhoods and on roads.

Yet there are numerous businesses and municipalities that thrive on population expansion. Plus, the shrinking birth rate raises questions about who will be the next generation of workers.

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Here’s what else I learned about Los Angeles County population trends …

2018 population: In a year, down 13,241 — fourth-worst among the 176 big U.S. counties. On a percentage basis, that’s down 0.13% — 22nd-worst nationally.

Decade’s population: Between 2010 and 2018 it grew 2.88% — No. 126 nationally.

International migration: Added 34,894 to population last year — third-largest gain nationally and up vs. 2010-17’s average of 33,816. That’s 3.19% growth, ranking No. 115.

Births last year: 119,254 — down 5.8% from the previous five years, 16th worst nationally.

Deaths last year: 61,543 — up 13.6% from the previous five years, 38th largest increase nationally.

Elsewhere in Southern California shows a movement inland …

Orange County: 20,104 domestic outflows — No. 167 nationally — and population growth of 6,018 — No. 64 nationally.

Riverside County: 18,980 domestic inflow — No. 4 nationally — and population growth of 33,534 — No. 5 nationally.

San Bernardino County: 1,543 domestic inflow — No. 50 nationally — and population growth of 18,400 — No. 18 nationally.