After states faced funding shortfalls because of Congress’s failure to reauthorize the Children’s Health Insurance Program (CHIP) by its original September 30, 2017, deadline, Congress last week finally agreed to fund an extension of the program for six years. This agreement was much needed for the children whose coverage hung in the balance at pivotal early stages of their lives.

Medicaid and CHIP are especially important to children’s health insurance coverage in small towns and rural areas, but most young children live in metropolitan areas. Our analysis shows that in 77 of the 100 metropolitan areas with the largest numbers of young children, Medicaid/CHIP covered more than 4 in 10 young children.

Medicaid and CHIP are critical for the youngest children

Medicaid and CHIP are crucial sources of coverage for children of all ages, but they are especially critical for the nation’s youngest children (ages 3 and younger). Nearly half (48.8 percent) of young children had Medicaid/CHIP coverage in 2015—the most common type of health insurance among children ages 3 and younger.

This pattern continued in 2016, with 48.5 percent of young children nationwide covered by Medicaid/CHIP—higher than the rate of 42.0 percent for older children. Just 3.3 percent of children ages 3 and younger were uninsured.

The high rate of Medicaid/CHIP coverage among young children in 2016 continued long-term trends. Under efforts to target uninsured children through eligibility expansions in Medicaid and CHIP, outreach, and simplifications to enrollment and renewal processes (as well as the coverage expansion to parents and new availability of Marketplace coverage under the Affordable Care Act), the rate of Medicaid/CHIP enrollment among children has been on the rise since the late 1990s, contributing to a drop in uninsurance among children of 63 percent between 1997 and 2016.

In metropolitan areas, Medicaid and CHIP are important to health care systems

We looked at coverage distributions among the 100 metropolitan statistical areas (MSAs) with the largest numbers of children ages 3 and younger in 2015 and 2016, which account for two-thirds of all young children nationwide.

Young children’s uninsurance rates in these 100 metropolitan areas averaged 3 percent and ranged from less than 2 percent in 27 metropolitan areas to more than 6 percent in 5 metropolitan areas: the Bridgeport, Connecticut; Brownsville, Texas; Corpus Christi, Texas; Lancaster, Pennsylvania; and Little Rock, Arkansas areas. (The high rate of uninsurance in the Lancaster, Pennsylvania, metropolitan area is likely related to its large Amish and Mennonite population, many of whom do not participate in traditional health insurance.)

We found high reliance on Medicaid/CHIP among young children in nearly all the 100 largest metropolitan areas, with an average Medicaid/CHIP coverage rate of 46.7 percent. In 77 of these 100 metropolitan areas, Medicaid/CHIP covered more than 4 in 10 young children, and for 37 of these, Medicaid/CHIP covered more than half of children ages 3 and younger, making these programs important to the health care systems for young children in both larger and smaller metropolitan areas.

Medicaid/CHIP covered more than 45 percent of young children in the five metropolitan areas with the largest numbers of young children: the New York City (48.5 percent), Los Angeles (54.4 percent), Chicago (45.5 percent), Dallas (47.9 percent), and Houston (48.9 percent) metropolitan areas.

But Medicaid/CHIP rates were also high in smaller metropolitan areas, across many states and regions. For example, about half of children in the Boise City, Idaho; Fayetteville, Arkansas; Syracuse, New York; and Tucson, Arizona, metropolitan areas were covered by Medicaid/CHIP. And among the 100 metropolitan areas with the largest numbers of children ages 3 and younger, most of the 15 with the highest rates of Medicaid/CHIP coverage among young children were small, with fewer than 65,000 young children in each (the exceptions were the Miami, Florida, and Riverside, California, areas). Each of these metropolitan areas had Medicaid/CHIP coverage rates among young children of nearly 60 percent or higher, with rates above 70 percent in the McAllen, Texas; Brownsville, Texas; and Fresno, California, metropolitan areas.

Medicaid/CHIP coverage among young children tends to be lowest in areas with high rates of employer coverage or nongroup or other coverage (including Marketplace coverage).

For instance, only about a quarter of young children in two metropolitan areas in Utah (the Ogden and Salt Lake City areas) and about a third of young children in two areas in California (the San Francisco and San Jose areas) were covered by Medicaid/CHIP, but all had rates of employer coverage of more than 60 percent. Medicaid/CHIP coverage was also low in the Honolulu area (31.9 percent), which had one of the highest rates of nongroup or other coverage (19.0 percent).

Following national patterns, Medicaid and CHIP provide health insurance for close to half of young children in their earliest years who live in metropolitan areas. Because parents of young children were also more likely than parents of older children to have Medicaid, Medicaid and CHIP play large roles in young children’s lives.

These programs not only form the basis for health care access in early childhood but also affect children’s long-term health and economic outcomes and families’ well-being and stability, ultimately helping them better contribute to their communities.

This article was originally posted on the Urban Institute’s Urban Wire.