  Ionized gas probes the influence of massive stars on their environment. The
Cygnus X region (d~1.5 kpc) is one of the most massive star forming complexes
in our Galaxy, in which the Cyg OB2 association (age of 3-5 Myr and stellar
mass $2 \times 10^{4}$ M$_{\odot}$) has a dominant influence. We observe the
Cygnus X region at 148 MHz using the Low Frequency Array (LOFAR) and take into
account short-spacing information during image deconvolution. Together with
data from the Canadian Galactic Plane Survey, we investigate the morphology,
distribution, and physical conditions of low-density ionized gas in a
$4^{\circ} \times 4^{\circ}$ (100 pc $\times$ 100 pc) region at a resolution of
2' (0.9 pc). The Galactic radio emission in the region analyzed is almost
entirely thermal (free-free) at 148 MHz, with emission measures of $10^3 <
EM~{\rm[pc~cm^{-6}]} < 10^6$. As filamentary structure is a prominent feature
of the emission, we use DisPerSE and FilChap to identify filamentary ridges and
characterize their radial ($EM$) profiles. The distribution of radial profiles
has a characteristic width of 4.3 pc and a power-law distribution ($\beta =
-1.8 \pm 0.1$) in peak $EM$ down to our completeness limit of 4200 pc
cm$^{-6}$. The electron densities of the filamentary structure range from $10 <
n_e~{\rm[cm^{-3}]} < 400$ with a median value of 35 cm$^{-3}$, remarkably
similar to [N II] surveys of ionized gas. Cyg OB2 may ionize at most two-thirds
of the total ionized gas and the ionized gas in filaments. More than half of
the filamentary structures are likely photoevaporating surfaces flowing into a
surrounding diffuse (~5 cm$^{-3}$) medium. However, this is likely not the case
for all ionized gas ridges. A characteristic width in the distribution of
ionized gas points to the stellar winds of Cyg OB2 creating a fraction of the
ionized filaments through swept-up ionized gas or dissipated turbulence.
